Ti-Ni-Cu形状记忆合金快速凝固条带的拉伸行为

Tensile Behavior of Rapidly Solidified Ti-Ni-Cu Shape Memory Alloy Ribbons

采用快速凝固法制备了Ti53.5Ni22.8Cu33.7合金薄带。用透射电镜（TEM）、电子探针（EPMA）和电子拉伸试验机对铸态和退火态下的条带进行力学分析、组织分析及断口形貌分析。研究发现，铸态下Ti53.5Ni22.8Cu23.7合金条带的抗拉强度和断裂应变分别为1257MPa和3．86％。其断口形貌有明显的脉状条纹和光滑非晶无特征区。条带经450℃退火10min和60min后其断裂强度分别为623MPa和850MPa，条带的弹性模量随着应变增加从7～10GPa增至25GPa。退火后条带拉伸断口均体现出等轴晶粒形貌。经450℃，60min退火的合金条带拉伸前后的TEM形貌特征不同，拉伸后的奥氏体晶粒中局部出现应力，诱发马氏体相变，从而形成马氏体板条。

The microstructure,mechanical properties and tensile fracture morphology of Ti53.5Ni22.8Cu23.7 shape memory alloy ribbons fabricated by rapid solidification were investigated by transmission electron microscope(TEM),electron probe microanalysis(EPMA)and tensile testing.The results show that tensile fracture stress and strain of as-cast ribbons reach 1 257 MPa and 3.86%,respectively,and the fracture morphology exhibits typical vein fringe and amorphous featureless zone.Tensile strength of the ribbons is reduced to 623MPa and 850MPa,respectively,after annealed at 450℃ for 10 min and 1 hour,meanwhile,with increasing in strain,elastic modulus of the ribbons is improved from 7~10GPa to 25GPa.Fracture morphology of annealed ribbons exhibits equiaxed grain.The TEM features of the ribbons annealed at 450℃ for 1 hour are different before and after tensile testing.Some martensite variants originated from martensite transformation induced by tensile stress can be observed in local austensite grain after tensile testing.