Microscopic Characterization of Semi-Solid Ti14 Alloy

摘要:

采用热模拟系统研究半固态变形参数对合金微观组织演变和元素分布的影响，并讨论变形过程中的Ti2Cu析出行为。结果表明：微观组织，特别是Ti2Cu析出过程受变形参数影响较大；温度的增加，应变速率和变形量的降低将促进Ti2Cu在晶界的偏析，最终形成了网状晶界结构。分析认为：半固态晶界的析出过程主要受控于包晶反应，升温或降低其他变形参数将有利于液相在晶界的析出，形成晶界Cu元素富集区。液相的偏析和Cu元素的富集增加了该区域的包晶反应，最终在冷却过程中形成了粗大的网状晶界结构

Abstract:

The microstructural evolution and the element distribution of Ti14 (α+Ti2Cu) alloy during semi-solid compression were investigated. Moreover, the Ti2Cu precipitate behaviors were discussed in detail. The results show that the microstructure, the number and distribution of Ti2Cu precipitates have significant dependence on the process parameters. More Ti2Cu will precipitate on grain boundaries at a higher deformation temperature, and/or a lower strain rate as well as deformation ratio, and finally a network structure is formed after deformation at 1100 °C. The precipitation on grain boundaries is found to be mainly controlled by peritectic reactions. The elevated temperatures resulted in more liquid along the prior grain boundaries, and a Cu-rich region is formed, finally. the “coarse” grain boundaries appear during re-solidification