Design and preparation of Ti-6Al-1.7Fe-0.1Si-7.3Cr alloy with excellent tensile properties

A novel Ti-6Al-1.7Fe-0.1Si-7.3Cr alloy was designed using high-throughput diffusion couple technique. The heat treatment effects on the microstructure and tensile properties of the designed alloy was investigated. The results indicated that the alloys after solution treatment at 800 °C/840 °C and aging at 400 °C/470 °C exhibited high strength (>1200 MPa) and good ductility (>5 %) due to the synergy of spherical αp phase, coarse flake αp phase and acicular αs phase in the β matrix. The precipitation of TiCr2 Laves phase at aging temperatures above 540 °C led to a decline in ductility. The absence of the spherical αp phase for the alloy after solution treatmen at 920 °C also resulted in the deterioration of aging elongation. Good balances of strength and ductility were achieved for the alloys after solution treatment at 840 °C and aging at 400 °C/470 °C, with the ultimate tensile strength and tensile elongation of 1237 MPa/23.3 % and 1753 MPa/5.1 %, respectively. Furthermore, the deformation mechanism of the alloys was analyzed, and dislocation slip in αp phase and β grain was demonstrated to be the main plastic deformation mode.

采用高通量扩散偶技术设计了一种新型Ti - 6Al - 1.7Fe - 0.1Si - 7.3Cr合金。研究了热处理对所设计合金的微观结构和拉伸性能的影响。结果表明，在800°C/840°C固溶处理以及400°C/470°C时效处理后的合金由于β基体中球形αp相、粗大片状αp相和针状αs相的协同作用，表现出高强度（>1200 MPa）和良好的延展性（>5%）。在高于540°C的时效温度下TiCr2拉弗斯相的析出导致延展性下降。920°C固溶处理后的合金中球形αp相的缺失也导致时效伸长率变差。840°C固溶处理以及400°C/470°C时效处理后的合金实现了强度和延展性的良好平衡，其极限抗拉强度和拉伸伸长率分别为1237 MPa/23.3%和1753 MPa/5.1%。此外，分析了合金的变形机制，结果表明αp相和β晶粒中的位错滑移是主要的塑性变形模式。