热处理对激光立体成形新型Ti-6Al-6Mo合金显微组织和硬度的影响

Effect of heat treatment on the microstructure and hardness of a novel Ti-6Al-6Mo alloy formed by laser solid forming

摘要:

以混合元素粉末为原料,采用激光立体成形(Laser solid forming, LSF)技术制备新型Ti-6Al-6Mo合金。研究了沉积态试样的显微组织以及固溶时效处理对合金显微组织形成及硬度的影响。结果表明,本研究所采用的热处理制度对原始β晶粒形貌没有显著的影响；固溶温度、固溶时间和固溶后的冷却方式对原始β晶粒中α相的形貌和尺寸以及LSF Ti-6Al-6Mo合金的显微硬度均有显著影响。当时效时间超过4小时后,随着时效时间的延长,合金的显微组织和显微硬度均未产生明显变化。基于不同热处理条件下LSF Ti-6Al-6Mo合金中初生α板条和次生α板条的析出机制及其对β基体的强化作用分析,揭示了热处理对LSF Ti-6Al-6Mo合金的显微组织和显微硬度的影响机理。

Abstract:

A novel Ti-6Al-6Mo alloy sample was fabricated by laser solid forming (LSF) using blended elemental powders as raw material. The microstructure of as-deposited sample and the effects of solution and aging treatment on the microstructure and microhardness of LSF Ti-6Al-6Mo alloy were discussed. The results showed that the heat treatment conducted in this study has no significant effect on the morphologies of prior b grains of the alloy. The solution temperature, solution time, and the cooling method after solution treatment have a significant effect on the morphology and size of the α phase in the prior β grains and the microhardness of the LSF Ti-6Al-6Mo alloy. When the aging time exceeds 4 hours, the microstructure and microhardness of the alloy change little with increasing aging time. Based on the analysis of precipitation and strengthening effect of the primary α laths and secondary α laths on the b matrix in LSF Ti-6Al-6Mo alloy under different heat treatment conditions, the influence mechanism of heat treatment on the microstructure and microhardness of LSF Ti-6Al-6Mo was revealed.