拉伸和恢复性能的影响
(1. 东北大学 材料物理与化学研究所，沈阳110004; 2. 中国科学院 金属研究所，沈阳110016)
摘 要: 采用XRD、SEM和拉伸试验机对热轧Ni47Ti44Nb9形状记忆合金板材的织构及其对拉伸和恢复性能的影响进行研究，以便为改善该合金的力学和记忆性能提供理论依据。热轧板材的织构主要为{001}áuv0ñ和{111}áuvwñ丝，沿轧向(RD)，{001}áuv0ñ丝织构中强组分向{001}á010ñ靠近，{111}áuvwñ丝织构中的{111}á112ñ和{111}á165ñ组分较强；沿横向(TD)，强织构组分为{001}á010ñ和{111}á132ñ；热轧板材经高于再结晶温度热处理后，沿轧向，应力诱发马氏体相变临界应力最高，与轧向成45˚角方向的临界应力最低，且沿横向拉伸断口表面出现很多微裂纹；经850 ℃热处理后，临界应力随着冷速的加快而降低，且该温度下退火板材的织构对可恢复应变的影响不明显，基本在7.0%~7.4%。
关键字: Ni47Ti44Nb9形状记忆合金；织构；拉伸性能；恢复应变；断裂
hot-rolled Ni47Ti44Nb9 shape memory alloy sheet
（1. Institute of Materials Physics and Chemistry, Northeastern University, Shenyang 110004, China;
2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The texture and its influence on tensile and recoverable properties of hot-rolled Ni47Ti44Nb9 shape memory alloy sheet were studied by XRD, SEM and tensile tester to provide theoretic basis for improving mechanical and memory properties of the alloy. The main textures of hot-rolled sheets are {001}áuv0ñ and {111}áuvwñ fibres. The strong components in {001}áuv0ñ fibre approach to {001}á010ñ component, and {111}á112ñ and {111}á165ñ components are stronger in {111}áuvwñ fibre along RD. The {001}á010ñ and {111}á132ñ are the strong components along TD; The critical stress of stress-induced martensite transformation along RD is the maximum and the minimum is along 45˚ to RD for hot-rolled sheet heat-treated at temperature higher than the recrystallization temperature, and some micro-cracks appear on the fracture surface of the specimen tensioned along TD. The critical stress decreases with increasing the cooling rate at 850 ℃, and texture has no obvious influence on the recoverable strain whose values are basically in the range of 7.0%−7.4% for sheet annealed at 850 ℃.
Key words: Ni47Ti44Nb9 shape memory alloy; texture; tensile property; recovery strain; fracture
