Invited Speaker

Abstract: (Ti5Si3+TiBw)/Ti6Al4V titanium alloy matrix composites with two-scale network architecture were designed and successfully fabricated by reaction hot pressing. TiB whiskers (TiBw) were synthesized in situ around the Ti6Al4V matrix particles and formed the first-scale network structure. Ti5Si3 needles (Ti5Si3) were precipitated in the β phase around the exquiaxed α phase and formed the secondary-scale network structure. The results showed that the two-scale network structured composites exhibited more superior performances, such as, strength and ductility at room and high temperatures, high temperature oxidation resistance, high temperature creep resistance, and so on. The tensile strength can be increased to 1050MPa and 900MPa at 550℃ and 600℃ for Ti6Al4V matrix composites. In addition, the creep rate of the composites remarkably reduced by an order of magnitude compared with Ti6Al4V alloys. Moreover, the rupture time of the composites increased by 20 times, compared with Ti6Al4V alloys at 550℃/300 MPa. The superior creep resistance is attributed to the two-level hierarchical structures and the two-scale reinforcements. The TiB whisker reinforcement distributed in the first network boundary around Ti6Al4V matrix contributed to creep resistance primarily by blocking grain boundary sliding, while the nano-Ti5Si3 particles in the secondary network boundary (β phase) around α phase mainly by hindering phase boundary sliding. Such a (Ti5Si3+TiBw)/Ti6Al4V titanium alloy matrix composite is a candidate for the applications with low weigh and high temperature requirements.

Keywords. Titanium alloys, titanium matrix composites, structure, high temperature, mechanical properties

Biography: Professor Lin Geng is the dean of the School of Materials Science and Engineering, Harbin Institute of Technology, China. His research interests include aluminum alloys, titanium alloys, metal matrix composites, powder metallurgy, material design and optimization, etc. He has undertaken more than 40 projects from Chinese government, and co-authored ~400 SCI indexed international journal papers and 3 authored books. His speech title is "High temperature performance of (Ti5Si3+TiBw)/Ti6Al4V composites".