Ke Yang is a professor in Institute of Metal Research, Chinese Academy of Sciences. He is also the Fellow of International Union for Biomaterials Science and Engineering and the Fellow of Chinese Biomaterials Society. He is engaging in new metal materials for medical applications such as antibacterial metals, biodegradable metals, biofunctionalized metals, etc. He has published over 650 journal articles and been awarded more than 170 China patents.

Topic title: Additive manufacture of novel Cu-bearing titanium alloy with unique performance

Abstract:

The Cu-bearing titanium alloys such as Ti5Cu and Ti6Al4V5Cu are newly developed medical titanium alloys with antibacterial activities. As the problem of mismatch of high strength but poor ductility caused by the lath α’ martensitic microstructure of titanium alloys that usually forms after additive manufacturing (AM) has limited the broad application of materials, we developed a boundary engineering strategy for the Cu-bearing titanium alloy, aiming to synergistically enhance both strength and ductility of the AM fabricated titanium alloy. It is hypothesized that both low-angle and high-angle grain boundaries are beneficial to the strength of metals, however only high-angle grain boundaries can simultaneously improve both strength and ductility. Thus we efficiently refined the martensitic lath width from 500~1000 nm to 50~200 nm through Cu alloying in titanium alloy so as to increase the number of low-angle grain boundaries, as a result, the strength of the Cu-bearing titanium alloy was increased from 1090 MPa to 1460 MPa. Furthermore, we also tailored the prior β grain size from 1900 μm to 35 μm to increase the number of high-angle grain boundaries through both Cu alloying and controlling the melting pool size during the AM  process, therefore, the elongation of the alloy was increased from 3.6% to 11.2%. The Cu-bearing titanium alloy can provide a new way for realizing better combination of mechanical properties for AM fabricated titanium alloys.