固溶时效处理对Ni50Ti44Al6合金微观组织和力学性能的影响

采用扫描电子显微镜、X射线衍射、室温和高温压缩试验等方法研究了固溶时效对Ni₅₀Ti₄₄Al₆合金微观组织和力学性能的影响.Ni₅₀Ti₄₄Al₆合金的铸态微观组织是由NiTi基体和沿晶界分布的网状组织构成.随着固溶温度升高，合金中的网状组织部分消失，第二相在基体中趋向于均匀的弥散分布；随时效时间延长，合金的强度先升高后降低.固溶时效处理能有效改善Ni₅₀Ti₄₄Al₆合金的力学性能.最佳的处理制度为：合金在1150℃固溶6 h，水淬，再在700℃时效6 h.

Effect of solution and aging treatments on the microstructure and mechanical properties of a Ni50Ti44Al6 alloy

Scanning electron microscopy (SEM), X-ray diffraction (XRD) and compressive tests at room temperature and elevated temperatures were used to investigate the effect of solution and aging treatments on the microstructure and mechanical properties of a Ni₅₀Ti₄₄Al₆ alloy. The microstructure of the alloy includes NiTi matrix phase and a reticular structure which precipitates on grain boundaries. With the rising of solution treatment temperature, parts of the reticular structure vanish, and the second phase dissolves into the matrix and distributes more homogeneously. With the prolonging of aging time, the strength of the alloy firstly increases and then decreases. Heat treatment can obviously improve the mechanical properties of the alloy. The optimal heat treatment regime was obtained as follows:solution treatment at 1 150℃ for 6 h, water-cooling and then aging at 700℃ for 6 h.