摘要
用ＪＥＭ２０００ＥⅫ高分辨电子显微镜（ＨＲＥＭ）研究了ＴｉＢ晶须增强的Ｔｉ合金基复合材料的精细结构分析了ＴｉＢ晶须的生长形貌和堆垛层错、β—Ｔｉ的超结构及ＴｉＢ和Ｔｉ合金基体界面．
The composite of Ti-6Al-4V matrix with discontinous TiB whiskers for reinforcement was successfully fabricated by standard powder metallurgy technique and hot extrusion. HREM studies were Performed using thin foils sectioned both parallel and perpendicular to the extrusion direction. The HREM specimens were prepared using standard techniques involving mechanical grinding, dimpling and ion milling. The morphology and atomic structure of the TiB whiskers, Ti-6Al-4V matrix and interfaces between TiB and matrix were investigated in a topeentry JEOL 2000EX Ⅱ high resolution electron microscope with a point-to-point resolution of 0.21 nm.The TiB whiskers were embedded in the Ti alloy matrix uniformly. The cross sections of TiB were faceted with facets on the {220} and {200}(TiB). planes and always somewhat elongated in the [001] direction. The growth direction of TiB whisker is parallel to [010](TiB). The TiB needles range from 1 to 2μm in cross-sectional size and the aspect ratio is about 20 or higher after hot extrusion.The TiB whiskers contain a moderate number of stacking faults on the (100)(TiB). The stacking order of atom layers in a fault region is denoted as .....A B A B B B A B A B.....This is an intrinsic stacking faults, and the displacement vector isR = -{ 1 / 2[100]+1 / 4[001]}The Ti alloy matrix consists of α-Ti, and β-Ti, with hop and bee structure, resistively. The volume fraction of β-Ti is higher than that of α-Ti. A superstructure was also found in β-Ti.According to the SAED patterns and calculations of the transformation matrix, the orientation relationships between the α-Ti or β-Ti, and TiB were determined. There are three types of specific orientation relationships (O.R.) between β-Ti and TiB, i.e.Ⅰ: (100)(TiB)∥(100)(β-Ti); [010](TiB)∥[1010](β-Ti)Ⅱ: (100)(TiB)∥(110)(β-Ti); [010](TiB)∥[001](β-Ti)Ⅲ: (100)(TiB)∥(112)(β-Ti); [010](TiB)∥[1111](β-Ti)On the other hand, there is a unique orientation relationship between a-Ti and TiB:(001)(TiB)∥(0001)(α-Ti)∥[010](TiB)∥[1120](α-Ti)The interface between (100)(TiB)∥(112)(β-Ti), is quite smooth, sharp and free from any interfacial phase. The lattice mismatch of f=2.9% between (002)(TiB) and (110)(β-Ti) was completely accommodated by elastic strain of the lattice. Although (100)(TiB)∥(100)(β-Ti) interface is also atomically flat and free from any interfacial phase, some misfit dislocations were observed, since the lattice mismatch between TiB and β-Ti at the (100)(TiB) ∥(100)(β-Ti) interface is 8.15%. The features of the TiB/ α-Ti interface are quite similar to that of the TiB / α-Ti interface. The TiB whiskers are well bonded to the Ti alloy matrix, which improves the mechanical properties of composite.
出处
《材料研究学报》
EI
CAS
CSCD
1994年第3期276-282,共7页
Chinese Journal of Materials Research
基金
国家自然科学基金
国家高技术新材料领域专家委员会联合资助
关键词
晶须
界面
钛合金
金属复合材料
Ti alloy matrix composite, TiB whisker, High resolution electron microscopy, Interface structure
