Abstract Three alloys with composition range of Ti-(25–35)Al (atomic %) were in-situ investigated using neutron diffraction to clarify the phase stability and equilibria in the Ti-rich part of the Ti–Al binary system. The phase transformation sequences of these three alloys were identified based on the neutron diffraction results and differential scanning calorimetry. No superstructure diffraction of β0 has been found in the neutron diffraction patterns. It is concluded that the β0 phase in the examined composition range is thermodynamically unstable. Based on the phase transformation sequences of these three alloys, combining the characters of congruent type relationship and peritectoid type relationship, the phase equilibria among β, α and α2 phases were confirmed as a peritectoid type, with two peritectoid reactions, i.e., β+α→α2 and β +α2→α.

中文翻译：

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Ti-Al二元体系富Ti部分相稳定性和平衡的原位中子衍射研究

摘要 使用中子衍射原位研究了三种成分范围为 Ti-(25-35)Al（原子百分比）的合金，以阐明 Ti-Al 二元体系中富钛部分的相稳定性和平衡。基于中子衍射结果和差示扫描量热法确定了这三种合金的相变序列。在中子衍射图中没有发现 β0 的超结构衍射。得出的结论是，所检查的组成范围内的 β0 相在热力学上是不稳定的。根据这三种合金的相变序列，结合全等型关系和包晶型关系的特点，确定β、α和α2相之间的相平衡为包晶型，有两个包晶反应，即β+α →α2 和 β +α2→α。