Ti-60Ta合金快速凝固过程中的相变研究

Research on Phase Transformation of Ti-60Ta Alloy during Rapid Solidification

摘要:

本文采用真空自耗电弧熔炼和热锻技术制备出Ti-60Ta合金棒，用PREP制粉技术制备出其球形粉末，并对棒材取块样进行高温淬火处理。利用SEM、XRD、TEM、DSC等分析手段对Ti-60Ta合金在快速凝固过程中的相变行为进行了研究。结果表明，Ti-60Ta原始块样和Ti-60Ta合金粉末主要以bcc结构的β相为主；随着粉末粒径减小，快速凝固过程中冷却速率增高，α"马氏体相逐渐增多，β相逐渐减少；原始块样经过1000℃/60min保温、淬火处理，生成了少量α"马氏体相；TEM图像和电子衍射斑点分析表明，在冷却速率更高的Ti-60Ta合金粉末中观察到板条状α "马氏体，宽度大约为50纳米，α"马氏体相优先生成于晶界处。

Abstract:

In this study, the Ti-60Ta alloy bars were prepared by vacuum arc smelting and then forging process. The bulk samples of Ti-60Ta alloy were cut from the bars, some of them were quenched in the water. The spherical powder of Ti-60Ta alloy were prepared by PREP (plasma rotating electrode process). The microstructure and phase transition process were characterized by SEM, XRD, TEM, DSC and so on. It revealed that both of the bulk samples and powders were mainly composed of β-Ti with bcc structure. With the powder size decreasing, the cooling rate was increased during the rapid solidification process, the content of α" martensite phase increased, while the content of β-Ti decreased gradually. The bulk samples were kept at 1000℃ for 60min then quenched in the water, resulting in a small amount of α" martensite phase. The results of TEM and SEAD revealed the lath α" martensite phase with a width of 50 nanometers formed in the powders after rapid solidification, the α" martensite phase mainly precipitated at grain boundaries.