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J.Am. Cera.Soc.85I2864-6602002 urna Side-Surface Structure of a Commercial B-Silicon Carbide Whisker Lin Geng, Jie Zhang, Qing-Chang Meng, and Cong-Kai Yao School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, People's Republic of China The side surfaces of a reial B-sic whisker were ana- displayed f zigzag structure and were composed of Ized by calculating ce energy and observing the nes. In the present research, the side-surface microstructure of the The results indicated that the structure of iC whiskers was studied from the point of side surfaces displayed of zigzag strueture and were crystal str energy analysis and was examined using composed of (111],(110), and(100) crystal planes. high-resolution transmission electron microscopy (TEM) L. Introduction Il. Experimental Procedure ILICON CARBIDE(SiC) whiskers have been produced using numer of the Tws-100 B-SiC whiskers used ous methods. The commercial B-siC whiskers used in this report in the 0. 1-1.0 um and 30-100 um, respec- (Product TWS-100, Tokai Carbon Co. Ltd, Tokyo, Japan)were Preparation of asic whisker specimen that was suitable for prepared by a vapor-iquid-solid (VLS)technique. These whiskers have been widely used as an effective reinforcement and toughening hase in aluminum-matrix composites" and ceramic-matrix compo (a) tes. SiC-whisker-reinforced aluminum alloy(SICwAl) composites have shown high mechanical and physical properties' and have (112 ential use in various structural applications I composites are usually fabricated by wder-metallurgy techniques. 6,7 The nature of the Sic/alur minum terfaces in the SiCwAl composites that have been produced by the different techniques is obviously different, which, in turn, affects the mechanical and physical properties of the composites. Previous Al Sic research results have shown that the bonding strength of the sic/ aluminum interface in the SICwAl composites made using the ueeze-casting method is very high(higher than the matrix shear no interfacial reaction and mutual diffusion of elements has occurred at the interface. To explain the high bonding strength of the sicaluminum interface. a semicoherent bondin mechanism has been highlighted ,u In this mechanism. the melt aluminum-matrix alloy is considered to have crystallized on the urfaces of the Sic whiskers during squeeze casting, so that some _02Bm crystal-orientation relationships might exist between the Sic whisker nd the aluminum-alloy matrix According to this mechanism, the side-surface structure of the SiC whisker is important in the nature and erties of the sicaluminum surface in the sic Ye et al4 also found that the side surfaces of the sic whiskers were very important, in regard to the properties of the alumina(Al,O3 matrix composites The results of the studies on the crystal structure of the B-sic agonal and triangular) existed for the p-Sic whiskers and both were single-crystal structures with a face-centered cubic (fcc structure and grew along the [1lllfcs direction( that of the whisk SiC axis).-3 However, almost no research reports exist in regard to the side-surface structure of the B-sic whiskers. Liu et al. reported that the side surfaces of the B-SiC whiskers are(112ifce however. the results of nutt 2, 3 indicated that the side surfaces 0.2um Fig. 1. TEM images of the B-SiC whiskers (a)Side-Surface Structure of a Commercial -Silicon Carbide Whisker Lin Geng,† Jie Zhang, Qing-Chang Meng, and Cong-Kai Yao School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China The side surfaces of a commercial -SiC whisker were analyzed by calculating the surface energy and observing the microstructure of the whiskers. The results indicated that the side surfaces displayed a type of zigzag structure and were composed of {111}, {110}, and {100} crystal planes. I. Introduction SILICON CARBIDE (SiC) whiskers have been produced using numerous methods.1 The commercial -SiC whiskers used in this report (Product TWS-100, Tokai Carbon Co. Ltd., Tokyo, Japan) were prepared by a vapor–liquid–solid (VLS) technique. These whiskers have been widely used as an effective reinforcement and toughening phase in aluminum-matrix composites2,3 and ceramic-matrix composites.4 SiC-whisker-reinforced aluminum alloy (SiCw/Al) composites have shown high mechanical and physical properties5 and have potential use in various structural applications. SiCw/Al composites are usually fabricated by squeeze-casting and powder-metallurgy techniques.6,7 The nature of the SiC/aluminum interfaces in the SiCw/Al composites that have been produced by the different techniques is obviously different, which, in turn, affects the mechanical and physical properties of the composites. Previous research results have shown that the bonding strength of the SiC/ aluminum interface in the SiCw/Al composites made using the squeeze-casting method is very high (higher than the matrix shear strength), although no interfacial reaction and mutual diffusion of elements has occurred at the interface.8 To explain the high bonding strength of the SiC/aluminum interface, a semicoherent bonding mechanism has been highlighted.9,10 In this mechanism, the melt aluminum-matrix alloy is considered to have crystallized on the surfaces of the SiC whiskers during squeeze casting, so that some crystal-orientation relationships might exist between the SiC whisker and the aluminum-alloy matrix. According to this mechanism, the side-surface structure of the SiC whisker is important in the nature and properties of the SiC/aluminum surface in the SiCw/Al composites. Ye et al.4 also found that the side surfaces of the SiC whiskers were very important, in regard to the properties of the alumina (Al2O3) matrix composites. The results of the studies on the crystal structure of the -SiC whiskers have shown that two types of transverse sections (hexagonal and triangular) existed for the -SiC whiskers and both were single-crystal structures with a face-centered cubic (fcc) structure and grew along the [111]fcc direction (that of the whisker axis).11–13 However, almost no research reports exist in regard to the side-surface structure of the -SiC whiskers. Liu et al.11 reported that the side surfaces of the -SiC whiskers are {112}fcc; however, the results of Nutt12,13 indicated that the side surfaces displayed a form of zigzag structure and were composed of {111}fcc crystal planes. In the present research, the side-surface structure of the -SiC whiskers was studied from the point of crystal structure and energy analysis and was examined using high-resolution transmission electron microscopy (TEM). II. Experimental Procedure The diameter and length of the TWS-100 -SiC whiskers used in the present report were 0.1–1.0 m and 30–100 m, respectively. Preparation of a SiC whisker specimen that was suitable for J. J. Petrovic—contributing editor Manuscript No. 187309. Received January 23, 2002; approved April 2, 2002. † Author to whom correspondence should be addressed. Fig. 1. TEM images of the -SiC whiskers in transverse section ((a) triangular whisker and (b) hexagonal whisker). 2864 journal J. Am. Ceram. Soc., 85 [11] 2864–66 (2002)