Design of Ti-7Al-2V alloy with high specific strength by using cluster formula
(1. Key Laboratory for Materials Modification by Laser, Ion, and Electron Beams of Ministry of Education, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China;
2. State Key Laboratory of Light Alloy Casting Technology for High-end Equipment, Shenyang Research Institute of Foundry Co., Ltd., Shenyang 110022, China;
3. School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, China)
2. State Key Laboratory of Light Alloy Casting Technology for High-end Equipment, Shenyang Research Institute of Foundry Co., Ltd., Shenyang 110022, China;
3. School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, China)
Abstract: A near-α Ti-7Al-2V alloy was designed using cluster formula approach and prepared by laser additive manufacturing, whose specific strength is better than that of Ti-6Al-4V alloy. Its composition formula α-{[Al-Ti12](AlTi2)}15+β-{[Al-Ti14](V3)}2 features an enhanced α-Ti by increasing α unit proportion of 15/17 (with respect to 12/17 of Ti-6Al-4V alloy) and stabilized β-Ti via V alloying. This alloy possesses a good laser additive manufacturing processibility. At the as-deposited state, the microstructures are composed of fine basket-weave regions, coarse basket-weave regions and ultrafine α Widmanst？tten lath regions. The surface roughness of coarse basket-weave regions is much smaller than that of fine basket-weave regions and ultrafine α Widmanst？tten lath regions. The α-phase distribution in fine basket-weave regions is more uniform than that in the coarse basket-weave regions. Its ultimate tensile strength of 971-1005 MPa, yield strength of 891-921 MPa and elongation of 4.5%-6.6% are close to those of Ti-6Al-4V alloy, and particularly, its specific strength of 224-232 kN·m/kg is better than that of Ti-6Al-4V alloy.
Key words: Ti alloy; composition design; cluster-plus-glue-atom model; laser additive manufacturing; mechanical properties