【摘要】 采用扫描电镜、透射电镜和力学压缩实验研究了热处理对Ni-42Ti-8Al合金微观组织和力学性能的影响。结果表明,Ni-42Ti-8Al合金铸态组织由NiTi基体和沿晶界分布的(NiTi+Ni2TiAl)网状共晶组织组成,细小的规则排列的Ni2TiAl相与基体具有共格或半共格关系,产生沉淀强化效果。合金在1 090℃固溶处理5 h后,共晶组织基本全部溶解,经过600℃×26 h时效处理后,又重新在晶界处析出;时效温度升高到700℃,共晶组织呈均匀弥散分布。热处理使Ni-42Ti-8Al合金的高温压缩屈服强度随时效温度升高先升高后降低,合金存在一个最佳的时效温度(700℃),时效温度过高或过低时,均对合金的力学性能不利。更多还原

【Abstract】 Effects of heat treatment on microstructure and mechanical property of Ni-42Ti-8Al alloy were studied by scanning electron microscopy(SEM),transmission electron microscopy(TEM) and compressive test.The results show that the microstructure of as-cast Ni-42Ti-8Al alloy is composed of NiTi matrix and reticular eutectic structure around the grain boundaries,which is composed of NiTi and Ni 2 TiAl phase.Fine Ni 2 TiAl particles with regular arrangement are coherent or semi-coherent with NiTi matrix,causing precipitation strengthening effect.When the alloy is treated by solid solution at 1090 ℃ for 5 h,most eutectic structure is dissolved,and the precipitate around the grain boundaries again after aging treatment at 600 ℃ for 26 h.For aging at 700 ℃,the eutectic structure is distributed more dispesively.The compressive yield strength at high temperatures firstly increases and then decreases with rising aging temperatures.For Ni-42Ti-8Al alloy,an optimal aging temperature of 700 ℃ is obtained.When aging temperature is over or under 700 ℃,the strength of the alloy is reduced.更多还原