In modern β-solidified TiAl alloys, the decomposition of α₂ phase is frequently observed during heat treatment or high-temperature deformation of the alloys. In this study, high-temperature deformation and decomposition mechanisms of α₂ phase in a Ti-45Al-8.5Nb-0.2B-0.2W-0.02Y alloy are investigated. In a sample deformed at 800 °C, the precipitation of β_o(ω_o) phase is observed within the equiaxed α₂ phase. The nucleation of ω_o particles within the β_o matrix indicates the α₂→β_o→ω_o transformation. In addition, numerous γ phase precipitates form within the β_o(ω) areas. The α₂ lamellae decompose into ultrafine (α₂+γ) lamellae and coarsened γ lamellae via α₂→α₂+γ and α₂→γ transformation, respectively. Moreover, the ω_o phase nucleates within the ultrafine lamellae via α₂→ω_o transformation. However, in a sample deformed at 1000 °C, the nucleation of β_o particles is sluggish, which is caused by the efficient release of the internal stress via dynamic recrystallization (DRX). These results indicate that complex phase transformations can be introduced by the decomposition of α₂ phase in TiAl alloys with a high amount of β-stabilizing elements.

在现代 β 凝固 TiAl 合金中，在合金的热处理或高温变形过程中经常观察到α ₂相的分解。在本研究中，研究了 Ti-45Al-8.5Nb-0.2B-0.2W-0.02Y 合金中α ₂相的高温变形和分解机制。在 800 °C 变形的样品中，在等轴 α ₂相内观察到β _o (ω _o ) 相的沉淀。β _o矩阵内ω _o粒子的成核表明α ₂ →β _o →ω _o转换。此外，β _o内会形成大量 γ 相沉淀物_。(ω) 区域。α ₂薄片分别通过α ₂ →α ₂ +γ 和α ₂ →γ 转变分解为超细(α ₂ +γ) 薄片和粗化γ 薄片。此外，ω _o相通过α ₂ →ω _o转变在超细薄片内成核。然而，在 1000 °C 变形的样品中，β _o粒子的成核缓慢，这是由于动态再结晶（DRX）有效释放内应力造成的。这些结果表明通过分解 α ₂可以引入复杂的相变 TiAl 合金中含有大量 β 稳定元素。