Nanocrystalline Ti-Al-Mo-Zr-Si Alloy (TC11) by Laser Powder Bed Fusion In-situ Alloying

TC11 alloy is an important high temperate Ti alloy. Its laser in-situ alloying by powder bed fusion-laser beam (PBF-LB) has been explored in this study. Results show that it is feasible to print the TC11 alloy using elemental powders rather than pre-alloyed powder, in terms of high density and good combination of strength and ductility at both room and elevated temperatures, along with minor loss of composing elements. Interestingly, it is noticed that an unusual nanocrystalline microstructure has formed due to the use of ZrH₂ powder feedstock, partially explaining the reason for the good mechanical properties achieved. Finite element analysis has been employed to understand the in-situ alloying. Furthermore, a post processing by micro-arc oxidation (MAO) has been employed to the alloy, aiming to enhance its high-temperature oxidation resistance. The results make an implication that hydrides such as ZrH₂ may hold the promise to develop nanosized, advanced Ti materials through laser in-situ alloying, and MAO can be considered for PBF-LB prepared TC11 alloy.