This paper focuses on the fabrication of as-forged Ti46.5Al2Cr1.8Nb-(W, B) alloy via pulse current auxiliary isothermal forging (PCIF). The starting material composed of near gamma (NG) microstructure was fabricated by adopting pre-alloyed powders via hot pressing sintering (HPS) at 1300 °C. Isothermal compression tests were conducted at a strain rate range of 0.001–0.1 s−1 and a temperature range of 1125–1275 °C to establish the constitutive model and processing map. The optimal hot deformation parameters were successfully determined (in a strain rate range of 10−3–2.5 × 10−3 s−1 and temperature range of 1130–1180 °C) based on the hot processing map and microstructure observation. Accordingly, an as-forged TiAl based alloy without cracks was successfully fabricated by PCIF processing at 1175 °C with a nominal strain rate of 10−3 s−1. Microstructure observation indicated that complete dynamic recrystallization (DRX) and phase transformation of γ→α2 occurred during the PCIF process. The elongation of as-forged alloy was 136%, possessing a good secondary hot workability, while the sintered alloy was only 66% when tested at 900 °C with a strain rate of 2 × 10−4 s−1.
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机译：本文主要研究通过脉冲电流辅助等温锻造（PCIF）锻造Ti46.5Al2Cr1.8Nb-（W，B）合金。通过在1300°C下通过热压烧结（HPS）采用预合金粉末来制备由近伽玛（NG）微观结构组成的原材料。在0.001–0.1 s −1 的应变速率范围和1125–1275°C的温度范围内进行了等温压缩试验，以建立本构模型和加工图。成功确定了最佳热变形参数（在10 −3 –2.5×10 −3 s -1 的应变速率范围内）根据热加工图和显微组织观察，温度范围为1130–1180°C。因此，通过PCIF工艺在1175℃下以10 -3 s -1 的名义应变率成功地制造了无裂纹的TiAl基锻造合金。显微组织观察表明，在PCIF过程中发生了完全动态重结晶（DRX）和γ→α2的相变。锻造合金的伸长率为136％，具有良好的二次热加工性能，而在900°C下以2×10 −4 s的应变速率测试时，烧结合金的伸长率仅为66％。 -1 。
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