Abstract A cast Al–Si–Ti alloy was solution treated at 540 °C for different periods between 0 and 72 h to understand the evolution of intermetallic phases. Only an (Al,Si)3Ti intermetallic phase with a low Si content was found in the as-cast alloy. The (Al,Si)3Ti particles were converted partly into a lamellar structure, a eutectoid phase, consisting of a Si-rich phase and an Al phase during solution treatment. The amount of the lamellar structure increased with the solution treatment time, but the composition of either constitute was kept almost unchanged regardless of the solution treatment times. The lamellar Si-rich phase is (Al,Si)2Ti (τ2) with a TiSi2 (C49-type) structure based on thermodynamic calculations and high-resolution TEM analyses. FCC Al phase is the product residing between the τ2 lamellae after the completion of transformation from (Al,Si)3Ti to τ2 phase. A near-rational orientation relationship (OR) between the Al and τ2 phases is determined as Al [110]//τ2 [100], Al ( 1 1 ¯ 1 ¯ )//τ2 [060]. The phase transformation from (Al,Si)3Ti to τ2 being a result of the diffusion of Ti and Si within the original (Al,Si)3Ti particulates as well as the Si diffusion from the Al matrix during solution treatment is proposed. The formation of the lamellar structure in the microstructure is attributed mainly to the limited diffusivity of Ti element.

中文翻译：

---

固溶处理过程中Al-Si-Ti合金中金属间相的演变

摘要 将铸造的 Al-Si-Ti 合金在 540 °C 下固溶处理 0 到 72 小时之间的不同时间，以了解金属间相的演变。在铸态合金中仅发现具有低 Si 含量的 (Al,Si)3Ti 金属间相。(Al,Si)3Ti 颗粒在固溶处理过程中部分转化为层状结构，即共析相，由富硅相和铝相组成。层状结构的量随着固溶处理时间的增加而增加，但无论固溶处理时间如何，任一构成的组成几乎保持不变。基于热力学计算和高分辨率 TEM 分析，层状富硅相是 (Al,Si)2Ti (τ2)，具有 TiSi2（C49 型）结构。FCC Al 相是在完成从 (Al,Si)3Ti 到 τ2 相的转变后驻留在 τ2 薄片之间的产物。Al 和 τ2 相之间的近理性取向关系 (OR) 被确定为 Al [110]//τ2 [100], Al ( 1 1¯ 1 ¯ )//τ2 [060]。提出了从 (Al,Si)3Ti 到 τ2 的相变，这是 Ti 和 Si 在原始 (Al,Si)3Ti 颗粒中扩散以及固溶处理期间从 Al 基体扩散的结果。显微组织中层状结构的形成主要归因于 Ti 元素的有限扩散率。Si)3Ti 到 τ2 是 Ti 和 Si 在原始 (Al,Si)3Ti 颗粒中扩散以及固溶处理过程中从 Al 基体扩散的结果。显微组织中层状结构的形成主要归因于 Ti 元素的有限扩散率。Si)3Ti 到 τ2 是 Ti 和 Si 在原始 (Al,Si)3Ti 颗粒中扩散以及固溶处理过程中从 Al 基体扩散的结果。显微组织中层状结构的形成主要归因于 Ti 元素的有限扩散率。