(1. 西北工業(yè)大學(xué)材料學(xué)院 凝固技術(shù)國家重點(diǎn)實(shí)驗(yàn)室，西安 710072；
2. 西北有色金屬研究院，西安 710016)
摘 要: 利用Gleeble-3800型熱模擬試驗(yàn)機(jī)對經(jīng)過3次真空自耗熔煉的Ti-44Al-3Ta-0.3(Cr,W)(摩爾分?jǐn)?shù)，%)合金樣品進(jìn)行熱模擬等溫壓縮試驗(yàn)，研究該合金在1 150~1 250 ℃及0.01~1 s-1應(yīng)變速率下高溫變形后的宏觀與微觀組織演變。結(jié)果表明，在高溫變形過程中，變形使合金中的組織由粗大的鑄態(tài)γ/α2近片層組織演變?yōu)榧?xì)小的近等軸γ/α2組織。變形過程中原始片層組織發(fā)生了不同程度的動態(tài)再結(jié)晶，動態(tài)再結(jié)晶是引起組織演變的主要原因。該合金的動態(tài)再結(jié)晶形核主要由位錯(cuò)塞積和孿晶形核控制。最佳高溫塑形變形溫度為1 200 ℃，應(yīng)變速率小于1 s-1。
關(guān)鍵字: TiAl基合金；熱變形；組織演變；動態(tài)再結(jié)晶
（1. State Key Laboratory of Solidification Processing, School of Materials,
Northwestern Polytechnical University, Xi’an 710072, China;
2. Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China）
Abstract:The samples of Ti-44Al-3Ta-0.3(Cr,W) (mole fraction, %) were hot compressed in the temperature range of 1 200-1 300 ℃ and strain rate range of 0.01-1 s-1 for high temperature flow behavior and microstructure evolution study. The results show that the microstructure of the alloy evolves from as-cast big size γ/α2 to small size near-equiaxed γ/α2. The dynamic recrystallization (DRX) is the main reason that origin lamella changes during the hot deformation. The main nucleation mechanism of the DRX is controlled by the twins and the dislocation tangle growth. The optimum temperature for hot forming of the alloy is 1 200 ℃, and the strain rate is less than 1 s-1.
Key words: TiAl based alloy; hot deformation; microstructure evolution; dynamic recrystallization
