材料期刊网

用自蔓延燃烧合成法(SHS)制备了比较致密的NiTi合金, 并对经固溶和时效处理后的合金进行了X射线衍射和透射电子显微术 分析. 在样品中除了有热处理前就存在的Ti2Ni外, 又出现了两种相, 一种是已报道过的Ti11Ni14(又称Ti3Ni4), 为菱形结构(a=0.67 nm, alpha=113.85 circ), 它与基体 (B2结构, a=0.302 nm)的关系为: ＜1－11＞Ti11Ni14∥＜111＞B2, {1－10}Ti11Ni14}∥＜123＞B2. 另一种为新的时效析出相, 可用基体中部分Ti原子被Ni原子占据形成 的长程有序结构描述. 晶格常数为0.873 nm, 分子式 为Ti13Ni14. 它是一种时效析出亚稳相.

The phase constitution of a highly dense NiTi alloy prepared by combustion synthesis and treated at high temperature solution and aging was analyzed by X--ray diffraction and transmission electron microscopy (TEM). Two kinds of fine precipitates exist in the alloy besides Ti2Ni. One is the rhombohedral structure Ti11Ni14 (Ti3Ni4}) with a=0.67 nm and alpha=113.85 circ,  which has an orientation relationship with the matrix (B2 structure, a=0.302 nm): ＜111$＞Ti11Ni14∥＜111＞B2, {1－10＞Ti11Ni14∥{123}B2. Another one is an unreported metastable precipitate with a long range ordered structure caused by Ni at the positions of Ti in NiTi phase. Its lattice parameter (a=0.873 nm) is about 3 times of that of NiTi matrix and the molecular formula is Ti13Ni14.