Functionally gradient microstructure in Ti-Al-Cr (L1_0/L1_2) alloys under impact ultra-high pressure

Ti-Al-Cr (L1_0/L1_2) 合金在超高压冲击下的功能梯度显微组织

• 批准号: 12650704
• 负责人: TAKAHASHI Tomoshi
• 金额: $ 1.86万
• 依托单位: Niihama National College of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650704/
• 关键词: Ti-Al-Cr alloy system; Ultra-impact high pressure; L1_2 structure; Interdiffusion; Functionally gradient microstructure; Ll_2構造; Ti-Al-Cr合金

The interdiffusion experiments and the formation experiments of gradient microstructure have been performed in a temperature range from 1273 to 1573 K by using the diffusion couples of Ti/Ti-Al-Cr, Ti-Al/Ti-Cr and Ti-Al-Cr (Ll1_0) /TrAl-Cr (L1_2) alloys. Furthermore, the high-speed impact deformation experiments have been carried out in the above Ti alloys. (1)The gradient microstructure have been observed in each temperature. In the Ti/Ti-Al-Cr couples, the martensitic structure are formed near the Matano interface. The alloy couples soften at the composition hi the terminal alloy side, because of the formation of retained β phase.(2)The concentration profiles indicate that the diffusion distance of Cr is longer than that of Al in the solid solutions. The diffusion paths S-shaped curves. The binary and ternary interdiffusion coefficients are not sensitive to the solute concentrations.(3)The change in microstructure and hardness of Ti-38.1Al-4.8Cr (L1_0) alloys depend on cooling rate after the heat treatment at 1473 K for 24 h.

采用Ti/Ti-Al-Cr、Ti-Al/Ti-Cr和Ti-Al-Cr（L11_0）/TrAl-Cr（L1_2）扩散偶，在1273 ~ 1573 K温度范围内进行了互扩散实验和梯度组织形成实验。在此基础上，对上述钛合金进行了高速冲击变形实验。（1）在各个温度下观察到梯度显微组织。在Ti/Ti-Al-Cr偶中，马氏体组织在Matano界面附近形成。由于残余β相的形成，合金偶在末端合金侧的成分处软化。（2）固溶体中Cr的扩散距离大于Al的扩散距离。扩散路径呈S形曲线。二元和三元互扩散系数对溶质浓度不敏感。（3）Ti-38.1Al-4.8Cr（L1_0）合金在1473 K热处理24 h后，显微组织和硬度的变化取决于冷却速度。