Micron 67 (2014) 107–111
Contents lists available at ScienceDirect
Micron journal homepage: www.elsevier.com/locate/micron
Short communication
The deformation of B4 C particle in the B4 C/2024Al composites after high velocity impact Zhisong Zhou, Gaohui Wu ∗ , Longtao Jiang, Zhongguo Xu School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
a r t i c l e
i n f o
Article history: Received 25 June 2014 Received in revised form 22 July 2014 Accepted 22 July 2014 Available online 1 August 2014 Keywords: Metal matrix composites, Microstructure Crystal structure Plastic deformation Impact Focused ion beam (FIB)
a b s t r a c t In the present work, B4 C/2024Al composites with volume fraction of 45% were prepared by a pressure infiltration method. The microstructure of the crater bottom of B4 C/2024Al composite after impact was characterized by transmission electron microscope (TEM), which indicated that recovery and dynamic recrystallization generated in Al matrix, and the grain size distribution was about from dozens of nanometer to 200 nm. Furthermore, the plastic deformation was observed in B4 C ceramic, which led to the transformation from monocrystal to polycrystal ceramic grains. The boundary observed in this work was high-angle grain boundary and the two grains at the boundary had an orientation difference of 30◦ . © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Recently, B4 C ceramics, with lots of advantages such as high hardness and low density, have received much attention, which have been mainly applied as bulletproof materials (Orlovskaya et al., 2003; Savio et al., 2011; Vargas-Gonzalez et al., 2010), wear resistant materials (Ipek, 2005) and structure materials etc. It is interesting to note that B4 C has been used as bulletproof materials, which is mainly because of its high hardness and high Hugoniot elastic limit. Moynihan et al. (2002) showed that B4 C has good resistance capability under low-velocity impact. However, the resistant capability of B4 C is poor under high velocity impact. Dandekar (2001) indicated that the impact shear strength of B4 C decreased suddenly and the macroscopic damage morphology changed with the increasing impact pressure. Mingwei Chen et al. (2003) studied the micro-morphology of the B4 C target plate after bullet impact with velocity of 750–1000 m/s, which showed that the impact led to the formation of stacking faults and amorphous ribbons in B4 C particles, and thus the strength decreased with increasing speed. Interestingly, Blumenthal et al. (1994) shown that the Al matrix could improve the resistant ability of crack propagation in B4 C/Al composites. Blumenthal and Gray (1989a,b) studied the dynamic compressive properties and microstructure of B4C/Al composites
∗ Corresponding author. Tel.: +86 451 86402373 4070; fax: +86 451 86412164. E-mail addresses: [email protected] (Z. Zhou), [email protected] (G. Wu). http://dx.doi.org/10.1016/j.micron.2014.07.006 0968-4328/© 2014 Elsevier Ltd. All rights reserved.
with volume fracture of 65% under low rate impact, and found that the microstructure of B4 C remained virtually unchanged at the shock load of 5 GPa, moreover, dislocations and other defects were observed in B4 C particles at the shock load of above 10 GPa. Therefore, the damage mechanism of the B4 C ceramic plate by hot pressing under high velocity impact has already been revealed clearly. Recently, much attention (Naebe et al., 2013; Wu et al., 2012; Yazdani and Salahinejad, 2011; Zlotnikov et al., 2005) has been paid to B4 C/Al composites, which could reduce costs and improve fracture toughness of B4 C ceramics. However, the damage behavior and deformation mechanism of B4 C/Al composites under high velocity impact have been studied rarely. The previous reports (Liu et al., 2012) mostly discussed the properties of B4 C/Al composites under low speed, and the damage and deformation procedures have been studied rarely. The deformation behavior of B4 C/Al composites under high velocity impact has not been revealed clearly. In the present work, the microstructure of B4 C/2024Al composites under high speed impact was studied, and the deformation mechanisms were discussed and revealed. 2. Experimental B4 C/2024Al composites were prepared by pressure infiltration method with 45% volume fraction, and B4 C was single crystal particle with average particle size of 4.5 m. The shape of composite target was cylinder with diameter of 90 mm and thickness of about 53 mm. The 7.62 mm penetrator was used as bullet, with speed of
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Fig. 1. (a–c) The crater images of B4 C/Al composites after impact.
830 m/s and the incident direction of vertical target surface. The crater was formed by bullet impact with diameter of 24 mm and the depth of 7.7 mm, which is shown in Fig. 1(a). The composite target was cooled naturally in the air after the impact. Part of the crater was obtained by wire-electrode cutting as shown in Fig. 1(b).
Furthermore, the thin flake at the crater bottom was obtained from the part of the crater as shown in Fig. 1(c). The heat affected layer of above flake was removed by mechanical polishing, and the sample at the place shown in the figure was acquired (about 30 m to the bottom surface of the crater). Furthermore, transmission electron
Fig. 2. Microstructure of B4 C/Al composites before and after bullet impact characterized by TEM; (a) microstructure of the composites before impact; (b) the bright field image; (c) the amplification of part of (b); (d) the electron diffraction patterns.
Z. Zhou et al. / Micron 67 (2014) 107–111
microscope (TEM) sample was obtained by focused ion beam (FIB) on HELIOS NanoLab 600i. Moreover, the microstructure of B4 C/Al composites was characterized by TEM (Tecnai G2 F30 field emission transmission electron microscope).
3. Results and discussion 3.1. The Al matrix deformation after impact Fig. 2 shows the microstructure of B4 C/Al composites before and after bullet impact. The microstructure of the composites before bullet impact is shown in Fig. 2(a). It should be noted that the crystal boundary of Al matrix could not be observed, which indicated that the crystalline grains of the Al matrix were large, leading to that B4 C particles were wrapped inside the Al crystalline grains. Moreover, B4 C particles were perfect single crystal, and no dislocations and other defects were observed in the particles. It is interesting to note that recovery and recrystallization were observed in Al matrix after impact, and plenty of crystalline grains with size distribution from dozens nanometer to 200 nm were formed in Al matrix (Fig. 2(b)). Furthermore, it can be seen that parts of crystalline grains were sub-grains, and the boundaries were a set of parallel dislocations (Fig. 2(c)). The electron diffraction patterns show polycrystalline ring, which indicate that the orientations of most crystal grains in Al matrix distributed randomly. In the present work, the microstructure of two adjacent Al matrix grains on the same B4 C particle surface was characterized to reveal the degree
109
of the Al matrix deformation, as shown in Fig. 3. Fig. 3(a) shows the morphology of the two grains. Fig. 3(b) presents the electron diffraction patterns. After the index, spot A belongs to {1 1 1}Al . The acquired dark field images of spot A and B are shown in Fig. 3(c) and (b), respectively. Comparing Fig. 3(c) and (b), the orientation of the two Al grains differs greatly. Therefore, severe plastic deformation was formed in the Al matrix due to the bullet impact, which occurred in Al matrix between B4 C particles or on the B4 C particle surfaces. Ultra-fine grains were observed in steel, Mg and Ti alloy etc. after the dynamic compression under high strain rate (Hao et al., 2007a, 2007b, 2005). In the present work, the TEM sample was obtained at the bottom of the crater, which experienced high temperature and large deformation during the impact. Therefore, the ultra-fine grains in Al matrix were generated after the bullet impact. The similar results were observed by Qiang Guo et al. (2012) in TiB2 /Al composites.
3.2. The B4 C deformation after impact Fig. 4 presents the microstructure of the B4 C particle after bullet impact. The internal damage in B4 C particles after impact was directly observed in Fig. 4(a). The morphologies of region “a” and “b” were different, and region “c” was the boundary. The electron diffraction patterns of “b” and “c” were acquired as shown in Fig. 4(b) and (c), respectively. The B4 C is shown in Fig. 4(b). The two sets of B4 C patterns are shown in Fig. 4(c), which were
Fig. 3. The Al matrix grains around the B4 C particle; (a) the morphology image, (b) the electron diffraction patterns; (c) and (d) the acquired dark field images of spot A and B, respectively.
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Fig. 4. The deformation microstructure of B4 C; (a) the morphology image; (b) the electron diffraction patterns of “b” in (a); (c) the electron diffraction patterns of “c” in (a); (d) the high resolution image of “c” in (a); (e) and (f) the acquired dark field images of spot A and B, respectively.
both [1 2 3]B4C and have a phase difference of 30◦ . Blumenthal and Gray (1989a) reported that the local plastic deformation, twinning and stacking fault were formed in B4 C ceramics after impaction by 10.6 GPa impact pressure, which is consistent with the results in this work. The dark field images of “A” spot and “B” spot in Fig. 4(c) are shown in Fig. 4(e) and (f). It should be noted that three “grains” and two crystal orientations were formed in B4 C particle after impact as shown in Fig. 4(e) and (f). However, the B4 C particle still kept whole. Moreover, high resolution observation of spot
“c”, which was the boundary of “a” and “b” “grains”, is shown in Fig. 4(d). The upper part is grain “b”, and the lower part is grain “a”. It can be seen that there is a disorder region with a width of about 3 nm. Fourier transform was used on the two grains respectively, and the regeneration images were obtained. The results indicated that the two grains had a phase difference of 30◦ . Therefore, the disorder region in Fig. 4(d) was a high-angle grain boundary. It is interesting to note that the results were different with previous reports. Mingwei Chen et al. (2003) indicated that B4 C
Z. Zhou et al. / Micron 67 (2014) 107–111
generated planar defects under the impact with speed of 783 m/s. Furthermore, amorphous layers were formed in B4 C particles at the speed up to 907 m/s (the structure and crystallographic orientation on both sides of the amorphous layer stayed the same). In the present work, the TEM samples within 30 m to the bottom of the crater were obtained by the FIB method, which was difficult to obtain by traditional methods (Guo et al., 2012; Mingwei Chen et al., 2003). It should be noted that the increasing severe deformation were produced with the decreasing distance to the bottom of the crater. Therefore, more severe damage and deformation of B4 C particles was observed in this work after the bullet impact with speed of 830 m/s than the reported results. This result might be due to the closer distance to the bottom of the obtained TEM specimens. In this work, large plastic deformation of the B4 C particles in B4 C/2024Al composites was observed after high velocity impact, even though B4 C ceramics have very low fracture toughness. 4. Conclusions In this work, the microstructure of B4 C/2024Al composites after high velocity impact was characterized by TEM, and the TEM specimens were obtained at the bottom of the crater, which could provide direct evidence of the effect of high velocity impact on the microstructure of B4 C/2024Al composites. The according results are shown as follows: 1) It is interesting to note that the recovery and dynamic recrystallization were produced in the Al matrix after high velocity impact, and crystal grains with size distribution from dozens of nanometer to 200 nm were formed. 2) It should be noted that the interface of composites still kept well, and no interface delamination was observed after the high velocity impact. 3) The plastic deformation of B4C particle was observed, and B4C crystal was transformed from monocrystal to polycrystal after high velocity impact. Moreover, it should be noted that the boundary was high-angle grain boundary, and the two sides grains of the boundary had a phase difference of 30◦ .
111
References Blumenthal, W., Gray III, G., 1989a. Characterization of shock-loaded aluminuminfiltrated boron carbide cermets. In: Proceedings of the American Physical Society Topical Conference, Albuquerque, NM. Blumenthal, W., Gray III, G., 1989b. Structure–Property Characterization of a ShockLoaded Boron Carbide-Aluminum Cermet. Los Alamos National Lab., NM, USA. Blumenthal, W., Gray III, G., Claytor, T., 1994. Response of aluminium-infiltrated boron carbide cermets to shock wave loading. J. Mater. Sci. 29, 4567–4576. Chen, Mingwei, McCauley, J.W., Hemker, K.J., 2003. Shock-induced localized amorphization in B4C. Science 299, 1563, http://dx.doi.org/10.1126/science.1080819. Dandekar, D.P., 2001. Shock Response of Boron Carbide. Defense Technical Information Center Document. Guo, Q., Sun, D.L., Jiang, L.T., Han, X.L., Chen, G.Q., Wu, G.H., 2012. Residual microstructure associated with impact craters in TiB2/2024Al composite. Micron 43, 344–348. Hao, Y., Li, S., Sun, S., Zheng, C., Hu, Q., Yang, R., 2005. Super-elastic titanium alloy with unstable plastic deformation. Appl. Phys. Lett. 87, 091906. Hao, Y., Li, S., Sun, B., Sui, M., Yang, R., 2007a. Ductile titanium alloy with low Poisson’s ratio. Phys. Rev. Lett. 98, 216405. Hao, Y., Li, S., Sun, S., Zheng, C., Yang, R., 2007b. Elastic deformation behaviour of Ti–24Nb–4Zr–7.9 Sn for biomedical applications. Acta Biomater. 3, 277–286. Ipek, R., 2005. Adhesive wear behaviour of B4C and SiC reinforced 4147 Al matrix composites (Al/B4C–A1/SiC). J. Mater. Process. Technol. 162, 71–75. Liu, B., Huang, W.M., Huang, L., Wang, H.W., 2012. Size-dependent compression deformation behaviors of high particle content B4C/Al composites. Mater. Sci. Eng. A 534, 530–535. Moynihan, T., LaSalvia, J., Burkins, M., 2002. Paper Presented at the 20th International Symposium on Ballistics. Orlando, FL., pp. 23. Naebe, M., Sandlin, J., Crouch, I., Fox, B., 2013. Novel polymer-ceramic composites for protection against ballistic fragments. Polym. Compos. 34, 180–186. Orlovskaya, N., Lugovy, M., Subbotin, V., Rachenko, O., Adams, J., Chheda, M., Shih, J., Sankar, J., Yarmolenko, S., 2003. Design and manufacturing B4C–SiC layered ceramics for armor applications. In: Medvedovski, E. (Ed.), Ceramic Armor and Armor Systems. American Ceramic Society, Westerville, pp. 59–70. Savio, S.G., Ramanjaneyulu, K., Madhu, V., Bhat, T.B., 2011. An experimental study on ballistic performance of boron carbide tiles. Int. J. Impact Eng. 38, 535–541. Vargas-Gonzalez, L., Speyer, R.F., Campbell, J., 2010. Flexural strength, fracture toughness, and hardness of silicon carbide and boron carbide armor ceramics. Int. J. Appl. Ceram. Technol. 7, 643–651. Wu, H.Y., Zhang, S.C., Gao, M.X., Zhu, D., Pan, Y., Liu, Y.F., Pan, H.G., Oliveira, F.J., Vieira, J.M., 2012. Microstructure and mechanical properties of multi-carbides/(Al, Si) composites derived from porous B4C preforms by reactive melt infiltration. Mater. Sci. Eng. A 551, 200–208. Yazdani, A., Salahinejad, E., 2011. Evolution of reinforcement distribution in Al-B4C composites during accumulative roll bonding. Mater. Des. 32, 3137–3142. Zlotnikov, I., Gotman, I., Klinger, L., Gutmanas, E.Y., 2005. Combustion synthesis of dense functionally graded B4C reinforced composites. In: VanderBiest, O., Gasik, M., Vleugels, J. (Eds.), Functionally Graded Materials Viii. Trans Tech Publications Ltd., Zurich-Uetikon, pp. 685–691.
Contents lists available at ScienceDirect
Micron journal homepage: www.elsevier.com/locate/micron
Short communication
The deformation of B4 C particle in the B4 C/2024Al composites after high velocity impact Zhisong Zhou, Gaohui Wu ∗ , Longtao Jiang, Zhongguo Xu School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
a r t i c l e
i n f o
Article history: Received 25 June 2014 Received in revised form 22 July 2014 Accepted 22 July 2014 Available online 1 August 2014 Keywords: Metal matrix composites, Microstructure Crystal structure Plastic deformation Impact Focused ion beam (FIB)
a b s t r a c t In the present work, B4 C/2024Al composites with volume fraction of 45% were prepared by a pressure infiltration method. The microstructure of the crater bottom of B4 C/2024Al composite after impact was characterized by transmission electron microscope (TEM), which indicated that recovery and dynamic recrystallization generated in Al matrix, and the grain size distribution was about from dozens of nanometer to 200 nm. Furthermore, the plastic deformation was observed in B4 C ceramic, which led to the transformation from monocrystal to polycrystal ceramic grains. The boundary observed in this work was high-angle grain boundary and the two grains at the boundary had an orientation difference of 30◦ . © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Recently, B4 C ceramics, with lots of advantages such as high hardness and low density, have received much attention, which have been mainly applied as bulletproof materials (Orlovskaya et al., 2003; Savio et al., 2011; Vargas-Gonzalez et al., 2010), wear resistant materials (Ipek, 2005) and structure materials etc. It is interesting to note that B4 C has been used as bulletproof materials, which is mainly because of its high hardness and high Hugoniot elastic limit. Moynihan et al. (2002) showed that B4 C has good resistance capability under low-velocity impact. However, the resistant capability of B4 C is poor under high velocity impact. Dandekar (2001) indicated that the impact shear strength of B4 C decreased suddenly and the macroscopic damage morphology changed with the increasing impact pressure. Mingwei Chen et al. (2003) studied the micro-morphology of the B4 C target plate after bullet impact with velocity of 750–1000 m/s, which showed that the impact led to the formation of stacking faults and amorphous ribbons in B4 C particles, and thus the strength decreased with increasing speed. Interestingly, Blumenthal et al. (1994) shown that the Al matrix could improve the resistant ability of crack propagation in B4 C/Al composites. Blumenthal and Gray (1989a,b) studied the dynamic compressive properties and microstructure of B4C/Al composites
∗ Corresponding author. Tel.: +86 451 86402373 4070; fax: +86 451 86412164. E-mail addresses: [email protected] (Z. Zhou), [email protected] (G. Wu). http://dx.doi.org/10.1016/j.micron.2014.07.006 0968-4328/© 2014 Elsevier Ltd. All rights reserved.
with volume fracture of 65% under low rate impact, and found that the microstructure of B4 C remained virtually unchanged at the shock load of 5 GPa, moreover, dislocations and other defects were observed in B4 C particles at the shock load of above 10 GPa. Therefore, the damage mechanism of the B4 C ceramic plate by hot pressing under high velocity impact has already been revealed clearly. Recently, much attention (Naebe et al., 2013; Wu et al., 2012; Yazdani and Salahinejad, 2011; Zlotnikov et al., 2005) has been paid to B4 C/Al composites, which could reduce costs and improve fracture toughness of B4 C ceramics. However, the damage behavior and deformation mechanism of B4 C/Al composites under high velocity impact have been studied rarely. The previous reports (Liu et al., 2012) mostly discussed the properties of B4 C/Al composites under low speed, and the damage and deformation procedures have been studied rarely. The deformation behavior of B4 C/Al composites under high velocity impact has not been revealed clearly. In the present work, the microstructure of B4 C/2024Al composites under high speed impact was studied, and the deformation mechanisms were discussed and revealed. 2. Experimental B4 C/2024Al composites were prepared by pressure infiltration method with 45% volume fraction, and B4 C was single crystal particle with average particle size of 4.5 m. The shape of composite target was cylinder with diameter of 90 mm and thickness of about 53 mm. The 7.62 mm penetrator was used as bullet, with speed of
108
Z. Zhou et al. / Micron 67 (2014) 107–111
Fig. 1. (a–c) The crater images of B4 C/Al composites after impact.
830 m/s and the incident direction of vertical target surface. The crater was formed by bullet impact with diameter of 24 mm and the depth of 7.7 mm, which is shown in Fig. 1(a). The composite target was cooled naturally in the air after the impact. Part of the crater was obtained by wire-electrode cutting as shown in Fig. 1(b).
Furthermore, the thin flake at the crater bottom was obtained from the part of the crater as shown in Fig. 1(c). The heat affected layer of above flake was removed by mechanical polishing, and the sample at the place shown in the figure was acquired (about 30 m to the bottom surface of the crater). Furthermore, transmission electron
Fig. 2. Microstructure of B4 C/Al composites before and after bullet impact characterized by TEM; (a) microstructure of the composites before impact; (b) the bright field image; (c) the amplification of part of (b); (d) the electron diffraction patterns.
Z. Zhou et al. / Micron 67 (2014) 107–111
microscope (TEM) sample was obtained by focused ion beam (FIB) on HELIOS NanoLab 600i. Moreover, the microstructure of B4 C/Al composites was characterized by TEM (Tecnai G2 F30 field emission transmission electron microscope).
3. Results and discussion 3.1. The Al matrix deformation after impact Fig. 2 shows the microstructure of B4 C/Al composites before and after bullet impact. The microstructure of the composites before bullet impact is shown in Fig. 2(a). It should be noted that the crystal boundary of Al matrix could not be observed, which indicated that the crystalline grains of the Al matrix were large, leading to that B4 C particles were wrapped inside the Al crystalline grains. Moreover, B4 C particles were perfect single crystal, and no dislocations and other defects were observed in the particles. It is interesting to note that recovery and recrystallization were observed in Al matrix after impact, and plenty of crystalline grains with size distribution from dozens nanometer to 200 nm were formed in Al matrix (Fig. 2(b)). Furthermore, it can be seen that parts of crystalline grains were sub-grains, and the boundaries were a set of parallel dislocations (Fig. 2(c)). The electron diffraction patterns show polycrystalline ring, which indicate that the orientations of most crystal grains in Al matrix distributed randomly. In the present work, the microstructure of two adjacent Al matrix grains on the same B4 C particle surface was characterized to reveal the degree
109
of the Al matrix deformation, as shown in Fig. 3. Fig. 3(a) shows the morphology of the two grains. Fig. 3(b) presents the electron diffraction patterns. After the index, spot A belongs to {1 1 1}Al . The acquired dark field images of spot A and B are shown in Fig. 3(c) and (b), respectively. Comparing Fig. 3(c) and (b), the orientation of the two Al grains differs greatly. Therefore, severe plastic deformation was formed in the Al matrix due to the bullet impact, which occurred in Al matrix between B4 C particles or on the B4 C particle surfaces. Ultra-fine grains were observed in steel, Mg and Ti alloy etc. after the dynamic compression under high strain rate (Hao et al., 2007a, 2007b, 2005). In the present work, the TEM sample was obtained at the bottom of the crater, which experienced high temperature and large deformation during the impact. Therefore, the ultra-fine grains in Al matrix were generated after the bullet impact. The similar results were observed by Qiang Guo et al. (2012) in TiB2 /Al composites.
3.2. The B4 C deformation after impact Fig. 4 presents the microstructure of the B4 C particle after bullet impact. The internal damage in B4 C particles after impact was directly observed in Fig. 4(a). The morphologies of region “a” and “b” were different, and region “c” was the boundary. The electron diffraction patterns of “b” and “c” were acquired as shown in Fig. 4(b) and (c), respectively. The B4 C is shown in Fig. 4(b). The two sets of B4 C patterns are shown in Fig. 4(c), which were
Fig. 3. The Al matrix grains around the B4 C particle; (a) the morphology image, (b) the electron diffraction patterns; (c) and (d) the acquired dark field images of spot A and B, respectively.
110
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Fig. 4. The deformation microstructure of B4 C; (a) the morphology image; (b) the electron diffraction patterns of “b” in (a); (c) the electron diffraction patterns of “c” in (a); (d) the high resolution image of “c” in (a); (e) and (f) the acquired dark field images of spot A and B, respectively.
both [1 2 3]B4C and have a phase difference of 30◦ . Blumenthal and Gray (1989a) reported that the local plastic deformation, twinning and stacking fault were formed in B4 C ceramics after impaction by 10.6 GPa impact pressure, which is consistent with the results in this work. The dark field images of “A” spot and “B” spot in Fig. 4(c) are shown in Fig. 4(e) and (f). It should be noted that three “grains” and two crystal orientations were formed in B4 C particle after impact as shown in Fig. 4(e) and (f). However, the B4 C particle still kept whole. Moreover, high resolution observation of spot
“c”, which was the boundary of “a” and “b” “grains”, is shown in Fig. 4(d). The upper part is grain “b”, and the lower part is grain “a”. It can be seen that there is a disorder region with a width of about 3 nm. Fourier transform was used on the two grains respectively, and the regeneration images were obtained. The results indicated that the two grains had a phase difference of 30◦ . Therefore, the disorder region in Fig. 4(d) was a high-angle grain boundary. It is interesting to note that the results were different with previous reports. Mingwei Chen et al. (2003) indicated that B4 C
Z. Zhou et al. / Micron 67 (2014) 107–111
generated planar defects under the impact with speed of 783 m/s. Furthermore, amorphous layers were formed in B4 C particles at the speed up to 907 m/s (the structure and crystallographic orientation on both sides of the amorphous layer stayed the same). In the present work, the TEM samples within 30 m to the bottom of the crater were obtained by the FIB method, which was difficult to obtain by traditional methods (Guo et al., 2012; Mingwei Chen et al., 2003). It should be noted that the increasing severe deformation were produced with the decreasing distance to the bottom of the crater. Therefore, more severe damage and deformation of B4 C particles was observed in this work after the bullet impact with speed of 830 m/s than the reported results. This result might be due to the closer distance to the bottom of the obtained TEM specimens. In this work, large plastic deformation of the B4 C particles in B4 C/2024Al composites was observed after high velocity impact, even though B4 C ceramics have very low fracture toughness. 4. Conclusions In this work, the microstructure of B4 C/2024Al composites after high velocity impact was characterized by TEM, and the TEM specimens were obtained at the bottom of the crater, which could provide direct evidence of the effect of high velocity impact on the microstructure of B4 C/2024Al composites. The according results are shown as follows: 1) It is interesting to note that the recovery and dynamic recrystallization were produced in the Al matrix after high velocity impact, and crystal grains with size distribution from dozens of nanometer to 200 nm were formed. 2) It should be noted that the interface of composites still kept well, and no interface delamination was observed after the high velocity impact. 3) The plastic deformation of B4C particle was observed, and B4C crystal was transformed from monocrystal to polycrystal after high velocity impact. Moreover, it should be noted that the boundary was high-angle grain boundary, and the two sides grains of the boundary had a phase difference of 30◦ .
111
References Blumenthal, W., Gray III, G., 1989a. Characterization of shock-loaded aluminuminfiltrated boron carbide cermets. In: Proceedings of the American Physical Society Topical Conference, Albuquerque, NM. Blumenthal, W., Gray III, G., 1989b. Structure–Property Characterization of a ShockLoaded Boron Carbide-Aluminum Cermet. Los Alamos National Lab., NM, USA. Blumenthal, W., Gray III, G., Claytor, T., 1994. Response of aluminium-infiltrated boron carbide cermets to shock wave loading. J. Mater. Sci. 29, 4567–4576. Chen, Mingwei, McCauley, J.W., Hemker, K.J., 2003. Shock-induced localized amorphization in B4C. Science 299, 1563, http://dx.doi.org/10.1126/science.1080819. Dandekar, D.P., 2001. Shock Response of Boron Carbide. Defense Technical Information Center Document. Guo, Q., Sun, D.L., Jiang, L.T., Han, X.L., Chen, G.Q., Wu, G.H., 2012. Residual microstructure associated with impact craters in TiB2/2024Al composite. Micron 43, 344–348. Hao, Y., Li, S., Sun, S., Zheng, C., Hu, Q., Yang, R., 2005. Super-elastic titanium alloy with unstable plastic deformation. Appl. Phys. Lett. 87, 091906. Hao, Y., Li, S., Sun, B., Sui, M., Yang, R., 2007a. Ductile titanium alloy with low Poisson’s ratio. Phys. Rev. Lett. 98, 216405. Hao, Y., Li, S., Sun, S., Zheng, C., Yang, R., 2007b. Elastic deformation behaviour of Ti–24Nb–4Zr–7.9 Sn for biomedical applications. Acta Biomater. 3, 277–286. Ipek, R., 2005. Adhesive wear behaviour of B4C and SiC reinforced 4147 Al matrix composites (Al/B4C–A1/SiC). J. Mater. Process. Technol. 162, 71–75. Liu, B., Huang, W.M., Huang, L., Wang, H.W., 2012. Size-dependent compression deformation behaviors of high particle content B4C/Al composites. Mater. Sci. Eng. A 534, 530–535. Moynihan, T., LaSalvia, J., Burkins, M., 2002. Paper Presented at the 20th International Symposium on Ballistics. Orlando, FL., pp. 23. Naebe, M., Sandlin, J., Crouch, I., Fox, B., 2013. Novel polymer-ceramic composites for protection against ballistic fragments. Polym. Compos. 34, 180–186. Orlovskaya, N., Lugovy, M., Subbotin, V., Rachenko, O., Adams, J., Chheda, M., Shih, J., Sankar, J., Yarmolenko, S., 2003. Design and manufacturing B4C–SiC layered ceramics for armor applications. In: Medvedovski, E. (Ed.), Ceramic Armor and Armor Systems. American Ceramic Society, Westerville, pp. 59–70. Savio, S.G., Ramanjaneyulu, K., Madhu, V., Bhat, T.B., 2011. An experimental study on ballistic performance of boron carbide tiles. Int. J. Impact Eng. 38, 535–541. Vargas-Gonzalez, L., Speyer, R.F., Campbell, J., 2010. Flexural strength, fracture toughness, and hardness of silicon carbide and boron carbide armor ceramics. Int. J. Appl. Ceram. Technol. 7, 643–651. Wu, H.Y., Zhang, S.C., Gao, M.X., Zhu, D., Pan, Y., Liu, Y.F., Pan, H.G., Oliveira, F.J., Vieira, J.M., 2012. Microstructure and mechanical properties of multi-carbides/(Al, Si) composites derived from porous B4C preforms by reactive melt infiltration. Mater. Sci. Eng. A 551, 200–208. Yazdani, A., Salahinejad, E., 2011. Evolution of reinforcement distribution in Al-B4C composites during accumulative roll bonding. Mater. Des. 32, 3137–3142. Zlotnikov, I., Gotman, I., Klinger, L., Gutmanas, E.Y., 2005. Combustion synthesis of dense functionally graded B4C reinforced composites. In: VanderBiest, O., Gasik, M., Vleugels, J. (Eds.), Functionally Graded Materials Viii. Trans Tech Publications Ltd., Zurich-Uetikon, pp. 685–691.
