热处理对GTA增材制造TiAl合金组织与性能的调控

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.

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

The control of the microstructure and mechanical properties of deposited TiAl alloy with Al content of 45 at.% using heat treatment was studied. Based on the Ti-Al binary phase diagram, four heating temperatures were used: 1 080, 1 200, 1 270 and 1 350 ℃. 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 the γ phase 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 1 350 ℃ 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 1 200 ℃ 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.