NiAlMnFe高温形状记忆合金的马氏体相变行为

Martensitic transformation behaviors of NiAlMnFe high temperature shape memory alloy

用示差扫描量热仪、X射线衍射仪、扫描电镜及能谱仪、光学显微镜和显微硬度计等研究了固溶、时效工艺及热循环对Ni60Al19Mn16Fe5高温形状记忆合金马氏体(M)相变行为的影响。固溶淬火态以及固溶淬火加时效态Ni60Al19Mn16Fe5合金冷却、加热时发生可逆热弹性M相变。M相变温度、热滞和相变热随固溶温度的升高而增加,时效对M相变行为亦有较大影响,1100℃固溶处理和400℃时效处理后该合金具有良好的M相变行为。热循环几乎不影响正M相变,但第1次热循环时,M显示稳定性效应,使逆M相变推迟。第1次热循环后,逆M相变不再受热循环影响。该合金的固溶淬火组织为β'(M)+γ相,其中γ相约占20%,M的硬度高于γ相。

The effects of the solution and ageing treatment processes and thermal cycling on martensitic transformation (MT) behaviors of high temperature shape memory alloy Ni60Al19Mn16Fe5 were investigated by differential scanning calorimetry, Xray diffraction, SEM, energy dispersion Xray spectroscopy, optical microscopy and microhardness test. A reversible thermoelastic MT takes place during cooling and heating in the solution and ageingtreated Ni60Al19Mn16Fe5. The MT temperature, temperature hysteresis and transformation heat of the alloy increase with solution temperature increasing. The ageing treatment also strongly affects MT behaviors. An excellent MT behavior can be obtained from 400 ℃ ageing following 1 100 ℃ solution treatment. Thermal cycling is nearly no effect on the forward MT, but martensite shows stability effect in the first thermal cycle, and makes the reverse MT defer. After the first thermal cycle, the reverse MT is no longer affected by thermal cycling. The microstructure of the quenched Ni60Al19Mn16Fe5 alloy consists of martensite and gamma phase. The volume fraction of gamma phase is about 20%. The hardness of martensite is higher than that of gamma phase.