Cu－Zn－Al－Mn－Ni－Ti合金第二相形成过程研究

FORMATION OF SECOND PHASE IN Cu-Zn-Al-Mn-Ni-Ti SMA

加入微量Ｔｉ改变了Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ－Ｎｉ合金的凝固过程，凝固初期从液相优先结晶出树枝状Ｘ相，一次枝晶生长方向为〈１１１〉，在高温β相区固溶时Ｘ相球化形成稳定的Ｘ１相，同时析出Ｘｓ相Ｘｓ相以形核长大的方式从固相脱溶形成，其形貌、尺寸与处理温度、时间以及随后的冷却速度有关．随着温度升高，时间的延长，Ｘｓ相析出形态变化顺序如下：球形－立方形－梅花状－橄榄状．

The solidification of Cu-Zn-AI-Mn-Ni shape memory alloys may be changed by adding Ti.The dendritic X-phase may preferrentially precipitate at the initial stage out from liquid.The orientation of primary dendrite is〈 111〉.The X-phase spheroidizes and the stable Xl-phase precipitates during solid treatment in high temperature β-phase region.TEM observation showed that Xs-phase precipitated from β-phase nuclear-growth and its shape and size related to heat treatment temperature,holding time and cooling rate. By elevating temperature and prolonging time the shape variation of Xs-phase precipitated is in sequence of:globular, cubic,plum-blossom-like and rughy-shaped.