(1. 长安大学 材料科学与工程学院，西安 710064；
2. Waikato Centre for Advanced Materials and Manufacturing, University of Waikato, Hamilton 3240, New Zealand)
摘 要: 本研究设计了一种低成本短流程粉末冶金固结与加工技术制备了亚稳β型Ti-5553合金，主要包括快速粉末热压、单道次锻压和简单退火热处理。研究揭示了合金在加工过程中的组织演变机理、力学性能优化机理和组织性能关系。结果表明：经过在1275 ℃流动氩气气氛环境的快速热压，所得固结态合金相对密度高、宏微观组织均匀，无明显缺陷。经过单道次锻压及快速退火处理后，合金的微观组织和力学性能得以调控和优化，其微观组织和力学性能都对热处理温度的变化有较高的敏感性。当热处理温度为700 ℃和750 ℃时，合金展现出良好的强塑性匹配，抗拉强度和伸长率分别为1335 MPa和6.6%、1215 MPa和7.2%，原因是多级析出相的组织结构可同时稳固合金的力学性能强化效果、提高合金的均匀协调变形能力，使合金具有高强度和可接受的塑性。
关键字: 粉末冶金；亚稳β型钛合金；低成本；热加工；微观组织
（1. School of Materials Science and Engineering, Chang’an University, Xi’an 710064, China;
2. Waikato Centre for Advanced Materials and Manufacturing, University of Waikato, Hamilton 3240, New Zealand）
Abstract:A fast and cost-affordable processing route has been designed to manufacture powder metallurgy metastable β titanium alloy Ti-5553, containing rapid powder consolidation, one-step thermomechanical processing and fast heat treatment. Microstructure evolution mechanism, property optimization mechanism and microstructure-property relationship of the alloy during whole processing route were uncovered and elucidated thoroughly. The results show that the homogeneous macrostructure with high relative density but without obvious defects is achieved for the alloy after thermomechanical powder consolidation. The microstructure and mechanical properties of the processed alloy show high sensitivity to the heat treatment temperature. Specifically, the microstructural regulating and mechanical property optimization are successfully realized after one-step forging and fast annealing for one hour, with satisfactory strength(YS)-ductility(εf) combinations of 1335 MPa and 6.6% at 700 ℃, and 1215 MPa and 7.2% at 750 ℃, respectively. It is deduced that the hierarchical precipitation structure can stabilize the strengthening effect and improve the compatible deformation ability, which is beneficial for the concurrent high strength and moderate ductility.
Key words: powder metallurgy; metastable β titanium alloy; cost-effective; thermomechanical processing; microstructure
