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利用OM、XRD、SEM、EDS和DSC等分析测试手段研究了不同热处理方式对60NiTi合金中第二相析出,及其对马氏体转变和硬度的影响。结果表明:固溶后水淬处理能显著提高铸态60NiTi合金的硬度,但炉冷处理却显著降低合金的硬度。400℃时效略微降低固溶后水冷合金的硬度,但长时间时效对硬度的影响不大。Ni_3Ti相的大量固溶是固溶水冷处理显著提高铸态合金硬度的原因,而固溶后炉冷合金硬度下降则来源于更多Ni_3Ti相的析出。60NiTi合金的硬度取决于马氏体转变发生的难易程度。
The effects of different heat treatment methods on the precipitation of second phase in 60NiTi alloy and its effect on the martensitic transformation and hardness were studied by OM, XRD, SEM, EDS and DSC. The results show that the hardness of as-cast 60NiTi alloy can be remarkably improved by the solution quenching after solution treatment, however, the furnace cooling treatment significantly reduces the hardness of the alloy. 400 ℃ aging slightly reduce the hardness of the water-cooled alloy after solution, but the long time aging has little effect on the hardness. The large amount of solid solution of Ni_3Ti phase is the reason that the solid solution water cooling treatment significantly increases the hardness of the as-cast alloy, while the decrease of the hardness of the solution alloy after solution heat treatment comes from the precipitation of more Ni_3Ti phase. The hardness of 60NiTi alloy depends on the ease of martensite transformation.