加热温度对定向凝固Ni-45Ti-5Al合金组织特征的影响
Effect of Heating Temperature on Microstructure of Directionally Solidified Ni-45Ti-5Al Alloy
杨春雷1， 张晓丽2， 郑立静1， 张 虎1
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作者单位：(1. 北京航空航天大学 材料科学与工程学院, 北京 100191； 2. 解放军军事交通学院, 天津 300161)
中文关键字：Ni-45Ti-5Al合金； 定向凝固； 微观组织； 加热温度
英文关键字：Ni-45Ti-5Al alloy; directional solidification; microstructure; heating temperature
中文摘要：采用液态金属冷却定向凝固技术研究了Ni-45Ti-5Al (原子分数，%)合金在1450、1550和1650 ℃下定向凝固组织的演变规律。结果表明，Ni-45Ti-5Al合金定向凝固生长区宏观组织为柱状晶，定向效果良好；微观组织呈胞状晶形态生长，由初生NiTi基体相和Ti2Ni析出相组成；NiTi相和Ti2Ni相分别以[100]和[111]方向择优取向，两相组织均固溶有一定量Al，且基体相中Al含量大于析出相中Al；随加热温度的升高，定向胞晶组织变化不明显，胞晶间距为30～50 μm，在1550 ℃定向凝固时Ti2Ni相析出量最大。
英文摘要：The microstructure evolution of Ni-45Ti-5Al (at,%) alloy prepared by directional solidification with liquid-
metal-cooling at 1450 ℃, 1550 ℃ and 1650 ℃, respectively, was investigated. The results show that the macro-structure in directional solidification growth is columnar grain. The effect of directional solidification is good. The microstructure grows in cellular form, which is composed of primary NiTi matrix and Ti2Ni precipitates. The preferred orientation of NiTi and Ti2Ni is respectively [100] and [111] direction. Aluminum dissolves in both NiTi and Ti2Ni phase. The Al content in the matrix is higher than that in the precipitates. As the heating temperature increasing, the microstructure evolution is inconspicuous and the average cellular interval is 30～50 μm. The precipitation content of Ti2Ni is most when the heating temperature is 1550 ℃.