Hierarchical structure and deformation behavior of a novel multicomponent β titanium alloy with ultrahigh strength  

作　　者：X.Li X.N.Wang K.Liu G.H.Cao M.B.Li Z.S.Zhu S.J.Wu 

机构地区：[1]School of Materials Science and Engineering,Beihang University,Beijing 100191,China [2]Titanium Alloys Laboratory,Beijing Institute of Aeronautical Material,Beijing 100095,China [3]School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China

出　　处：《Journal of Materials Science & Technology》2022年第12期227-242,共16页材料科学技术（英文版）

基　　金：financial support from “13th five-year plan” equipment pre-research project of China (41422010501)。

摘　　要：Based on the general [Mo] equivalent criterion and d-electron orbital theory, a new ultrahigh-strength βtitanium alloy with eight major elements(Ti-4.5Al-6.5Mo-2Cr-2.6Nb-2Zr-2Sn-1V, TB17) for industrial applications was developed. An ingot of five tons was successfully melted by thrice vacuum consumable arc melting. The microstructure and elements partitioning of different conditions were investigated systematically. The results suggest that the hierarchical structures of micro-scale first α phase(αf), nano-scale secondary α phase(αs), and ultrafine FCC substructures can be tailored by solution plus aging(STA) heat treatment. The lateral and epitaxial growth of αfphase promotes the HCP-α to FCC substructure transformation with the help of elements partitioning during the aging process. Moreover, the element V, generally regarded as β stabilizer, is found to mainly concentrate in the Al-rich αfphase in this study probably due to its relatively lower content and the strong bonding energy of Al-V. The hierarchical structure has a strong interaction with dislocations, which contributes to achieve a superhigh strength of 1376 MPa.In addition, the plastic strain is partitioned in the multi-scale precipitates(such as the α and FCC substructures) and β matrix, resulting in a considerable plasticity. TEM observation demonstrates that high density entangled dislocations at interfaces and mechanical twins exist in the STA sample after tensile test. It can be deduced that both dislocation slipping and twinning mechanisms are present in this alloy.Therefore, TB17 alloy can serve as an excellent candidate for structural materials on aircrafts that require high strength and lightweight.

关 键 词：Titanium alloy Hierarchical structure Deformation behavior Ultrahigh strength Elements partitioning 

分 类 号：TG146.23[一般工业技术—材料科学与工程]