While Ti–Nb binary alloys have been extensively studied over the years, there are discrepancies in the literature relating to the β-α″ martensitic transformation that indicate an incomplete understanding. In particular, there are inconsistencies regarding the phase constitution of as-quenched material and the ability for α″ phase to be thermally-induced. To resolve these issues, the β-α″ phase transformation is studied in a Ti–24Nb (at.%) alloy subjected to two different water quench conditions. It is demonstrated that only the fastest quench rates (≳500 °C/s) result in the formation of α″ phase, and these materials exhibit a reversible thermally-induced β-α″ transformation at low temperatures. In contrast, slightly slower water quench procedures lead to a β+ω microstructure, and these samples do not exhibit a thermally-induced β-α″ transformation, even when cooled to −168 °C. Despite this, room temperature mechanical testing results indicate that α″ can be induced by stresses as low as 200 MPa. To explain these results, it is proposed that quenching stresses play a role in the competition between α″ and athermal ω phases at rapid quench rates. The present results are then reconciled with the body of literature and a broader understanding of phase stability in metastable β-titanium alloys.

尽管多年来对Ti-Nb二元合金进行了广泛的研究，但有关β-α''马氏体相变的文献中存在差异，这表明人们对其理解还不完全。特别地，关于淬火后的材料的相组成和α”相被热诱导的能力存在不一致。为了解决这些问题，研究了在两种不同水淬条件下的Ti–24Nb（at。％）合金中的β-α''相变。结果表明，只有最快的淬灭速度（≳500°C / s）会导致形成α”相，并且这些材料在低温下表现出可逆的热诱导β-α”相变。相比之下，稍微慢一些的水淬程序会导致β+ω微观结构，并且这些样品没有表现出热诱导的β-α''转变，即使冷却到−168°C时也是如此。尽管如此，室温机械测试结果表明，可以通过低至200 MPa的应力来诱发α''。为了解释这些结果，提出了淬灭应力在快速淬灭速率下在α''和无热ω相之间的竞争中起作用。然后，将当前结果与文献资料和对亚稳β-钛合金的相稳定性的更广泛理解相一致。