热型连铸柱晶CuAlNi合金丝记忆状态下的拉伸疲劳

Tensile Fatigue for in Memory State Columnar Grain CuAlNi SMA Wires Casted by Heated Mold Continuous Casting Process

用热型连铸法连铸了柱晶组织CuAlNi合金丝,在记忆状态下分别以4%,6%,8%应变量循环拉伸,以研究其疲劳性能。4%,6%应变下循环拉伸,变形以γ1′→β1″进行,断裂次数高达30000次以上。8%应变下以β1″的弹性变形进行,断裂次数急降到几百次。疲劳拉伸使晶界形成由马氏体组成的带状组织,松弛了应力集中,提高疲劳寿命。

Study on fatigue behavior in CuAINi SMA wires with columnar grains casted by heated mold continuous casting process was carried on cyclic tensile testing at 4%, 6% and 8% strains. The cyclic numbers at 4% and 6% strains are usually above 30000 because of the γ1′→β1″ deformation mode, whereas at 8 % strain the cyclic numbers drop drastically because the deformation mode of β1″ is elastic deformation. Tensile fatigue promotes the formation of stripe zones along the grain boundaries which contain mainly martensite, so as to relax the stress concentration in grain boundaries.