Microstructure and mechanical properties of additively manufactured Ti-6Al-4 V with trace cobalt additions
摘要
In this work, the effects of adding trace amounts of cobalt on the microstructure and mechanical properties of Ti-6Al-4 V alloys during arc additive manufacturing (WAAM) are investigated. The results show that during the melting process, the added Co particles will combine with oxygen at high temperatures to form the Co-Ox(CoTiO3, CoO, CoO3) phases. These phases act as non-uniform nucleation sites during the solidification of titanium alloys to promote grain refinement. Compared with unmodified Ti-6Al-4 V, the yield strength (YS) of Ti-6AI-4 V-Co alloy was increased from 855 to 950 MPa, and the tensile strength (UTS) was increased from 950 to 1050 MPa without any significant decrease in plasticity. Fine grain strengthening, solid solution strengthening and precipitation phase strengthening are the main reasons for the increase in the strength of titanium alloys after the addition of trace Co. Overall, the addition of trace cobalt can effectively regulate the microstructure of additively manufactured Ti-6Al-4 V alloy and optimize its mechanical properties. The results of the study provide a new idea for the design of high-performance titanium alloy materials.