Ni-Al-Fe系中NiAl(Fe)金属间化合物的析出强化

研究Ni-Al-Fe系中B2型金属间化合物NiAl(Fe)的硬度随时效时间的变化,同时测定时效处理后含析出相的NiAl(Fe)金属间化合物的屈服强度随温度变化。结果表明,在所有实验温度区域内,NiAl(Fe)化合物的屈服强度均远高于单相NiAl;析出相为体心立方结构的α-Fe相;在时效初期α-Fe相呈球状,过时效之后变成平行于有序基体{100}晶面的板条状。通过透射电镜观察还确定变形过程中位错滑移矢量为111。虽然α-Fe析出相的硬度低于NiAl(Fe)基体,但由于α-Fe析出相对运动位错有较强的钉扎作用而使基体得到强化。

Precipitation Hardening of NiAl(Fe) Intermetallic Compounds in Ni-Al-Fe System

Changes of hardness of B2-NiAl(Fe) intermetallic compounds in Ni-Al-Fe system with aging time and changes of yield strength of aged B2-NiAl(Fe) intermetallic compounds containing α-Fe precipitates with temperatures were investigated. Results show that the yield strength of B2-NiAl(Fe) intermetallic compounds containing α-Fe precipitates is higher than that of single phase NiAl at all the testing temperatures. It is revealed that the precipitates are disordered bcc Fe phase. The shape of a-Fe precipitates is sphericity and keeps coherent with the matrix in the initial aging period. With prolonging the aging time, the precipitates are platelet in shape, nearly parallel to the {100} planes of the B2-ordered matrix. TEM observation determines that the Burgers vector of the slipping dislocation is <111>. Although the hardness of α-Fe precipitates is lower than that of B2-NiAl(Fe) matrix, the pinning effect of the α-Fe precipitates on moving dislocation plays an important role in hardening of the B2-NiAl(Fe) matrix.