热处理对GTA增材制造TiAl合金组织与性能的调控

Control of the microstructure and mechanical properties of GTA-based wire arc additive manufactured TiAl alloys using post heat treatment

针对Al原子含量为45%的电弧沉积态TiAl合金,进行了基于热处理的组织与性能调控研究.结合Ti-Al二元相图分别制定了1080,1200,1270,1350℃4个加热温度,保温1 h后随炉冷却.结果表明,随着加热温度的升高,合金内偏析现象逐渐消失,晶界γ相减少,组织形态逐渐向全层片结构转变,且层片晶团尺寸逐渐增加.在1350℃下分别保温5,30 min和1 h,发现随着保温时间的延长,层片晶团逐渐粗化.基于单级热处理试验结果提出循环热处理工艺,将沉积态合金在900~1200℃之间多次循环“加热-短时保温-冷却”,获得了细小的层片晶团组织,合金硬度降低,抗压强度与压缩率均提高.

The control of the microstructure and mechanical properties of deposited Ti Al alloy with Al content of 45at.%using heat treatment was studied.Based on the Ti-Al binary phase diagram,four heating temperatures were used:1080,1200,1270 and 1350℃.Furnace cooling was applied after holding for 1 h.It was found that with the increase of the heating temperature,the segregation is gradually eliminated,and theγphase on the grain boundary decreases.The microstructure changes from two-state structure to full lamellar structure,and the lamellar colony size increases gradually.Preservate heat at 1350℃for 5,30 min and 1 h,respectively.It was found that the lamellar colony coarsened with the extension of holding time.Based on the single-stage heat treatment,the cyclic heat treatment process was proposed.The deposited parts were heated repeatedly between 900 to 1200℃and cooled after short-term insulation.The components with fine lamellar structure were obtained,whose hardness reduces,and the compressive strength and compression ratio both increase.