The athermal ω phase has been reported to be preferably formed at the quench rate below 10³ K/s in Ti-30 at.%Ta alloys. Contrary to this common viewpoint, this work presents a similar compositional alloy of Ti-28 at.%Ta with the existence of athermal ω fabricated by plasma rotating electrode process upon quenching at an ultra-high rate of 10⁴–10⁶ K/s. This study aims to probe the underlying mechanism for the athermal ω formation after ultra-rapid quenching of the Ti-28 at.%Ta. Microstructure and phase constituent of the ultra-rapid solidified (URS) Ti-28Ta were investigated. Results showed that the cellular-structured URS Ti-28Ta exhibited predominant β with martensitic α” and athermal ω. Elemental microsegregation is resulted in the URS Ti-28Ta with Ti atoms preferred to concentrate at the cellular walls while Ta accumulate in the matrix. Cellular walls are fully concentrated with martensitic α” and dislocations but free of ω, while the dislocation-free β matrix nearby the walls contains the athermal ω. The athermal ω is suppressed by the high-density dislocations at the grain boundaries, while compositional fluctuation due to the microsegregation in the metastable β matrix favor to form the athermal ω.

据报道， 在Ti-30 at。％Ta合金中，优选以低于10 ³ K / s的淬灭速率形成无热ω相。与这一普遍观点相反，这项工作提出了一种类似的Ti-28 at。％Ta的成分合金，并且存在以等离子旋转电极工艺以10 ⁴ –10 ⁶的超高淬火速度制造的无热ω。 千/秒 这项研究旨在探讨Ti-28 at.Ta的超快速淬火后无热ω形成的潜在机理。研究了超快速凝固（URS）Ti-28Ta的微观结构和相组成。结果表明，细胞结构的URS Ti-28Ta的β占主导，马氏体为α”，无热ω。元素的微偏析导致URS Ti-28Ta的Ti原子优先集中在细胞壁上，而Ta则在基质中积累。细胞壁完全集中有马氏体α”和位错，但没有ω，而壁附近的无位错β矩阵包含无热ω。晶界处的高密度位错抑制了无热ω，