定向凝固NiAl-32V亚共晶合金热稳定性研究

Investigation on the Thermal Stability of Directionally Solidified NiAl-32V Hypoeutectic Alloy

摘要:

本文采用定向凝固技术制备NiAl-32V伪二元亚共晶合金,研究该合金在高温热处理后不同抽拉速率稳态区组织形貌,并分析其热稳定性及组织形貌变化规律。结果表明：该合金初生相组织在900℃(5~100h)组织热稳定性良好；NiAl相共晶层片均有粗化与球化现象,且热处理时间越久,粗化程度越大,球化现象越明显。不同温度(900℃、1000℃、1100℃)5h高温热处理后该合金初生相面积占比也略有变化,所有试样(抽拉速率V=6～150μm/s)NiAl共晶层片均有粗化与球化现象；随着热处理温度的增加,粗化和球化现象愈明显。

Abstract:

In this paper, the NiAl-32V pseudo-binary hypoeutectic alloy was prepared by directional solidification technology. The microstructure morphology of the alloy in the steady-state region at different withdrawl rates after high temperature heat treatment was studied, and the variation of its thermal stability and microstructure morphology was analyzed. The results indicates: The primary phase of the alloy has good thermal stability at 900°C(5~100h). The coarsening and spheroidization of NiAl eutectic layers are observed, and the longer the heat treatment time is, the greater the coarsening degree is, and the more obvious the spheroidization is. After high temperature heat treatment at different temperatures(900°C,1000°C,1100°C)for 5 h, the proportion of primary phase area of the alloy also changed slightly. The coarsening and spheroidization of NiAl eutectic lamellae were observed in all samples (withdrawl rates V=6~150μm/s). With the increase of heat treatment temperature, coarsening and spheroidization are more obvious.