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采用差式扫描量热仪(DSC)、扫描电镜(SEM)和金相显微镜,研究了新型材料NiTiNb5合金经200～900℃热处理后的相变温度、相变滞后(As-Ms)、相变焓以及微观组织的变化。结果表明,当热处理温度低于700℃时,不论是锻态还是轧态,合金都没有出现马氏体及其逆相变,表明铸态NiTiNb5形状记忆合金经锻造或轧制后不再具有形状记忆效应,转变成结构材料;当热处理温度提高到800℃后,NiTiNb5合金锻态或轧态又出现较明显的马氏体及其逆相变,表明NiTiNb5合金经过合适的热处理,恢复了形状记忆效应。组织分析表明,800℃后的再结晶是NiTiNb5合金恢复“功能材料”特性的主要原因。
The phase transition temperature, phase transformation hysteresis (As-Ms) and phase transition of NiTiNb5 alloy after heat treatment at 200-900 ℃ have been studied by means of DSC, SEM and optical microscope. Enthalpy and microstructure changes. The results show that when the heat treatment temperature is lower than 700 ℃, whether forging or rolling state, the alloy does not appear martensite and its reverse phase transformation, indicating that as-cast NiTiNb5 shape memory alloy has no shape after forging or rolling Memory effect into structural materials; when the heat treatment temperature is raised to 800 ℃, NiTiNb5 alloy appears more obvious martensite and reverse phase change in forging or rolling state, which shows that NiTiNb5 alloy recovers shape memory after proper heat treatment effect. Tissue analysis shows that recrystallization at 800 ℃ is the main reason for the recovery of “functional material” properties of NiTiNb5 alloy.