BCC Lightweight Ti-Based Multi-Principal Element Alloy Ti₇₀Al₁₅Nb₁₀V₅ with Good Specific Strength and Ductility

Abstract: Lightweight alloys which reduce weight and improve the efficiency have the tendency of applications of structural materials. The balance between ductility and strength of lightweight multi-principal element alloys (LWMPEAs) is a hot research topic in this field at present. A novel body-centered cubic Ti-based LWMPEA Ti₇₀Al₁₅Nb₁₀V₅ was designed and developed. The as-cast alloy has α + β phases, coarse grains and relatively poor performance. Hot rolling was conducted and improved the mechanical properties of the alloy significantly. The rolled alloy has bcc matrix, finer grains and precipitates including B2 and O′ phases enhancing the strength. The tensile fracture mode is quasi-cleavage fracture. The density, specific yield strength and non-proportional elongation of this alloy are 4.78 g/cm³, 153.67 MPa cm³/g and 15.2%, respectively. The article compares several different design strategies for Ti-based multi-principal element alloys and analyzes the strengthening factors of the rolled alloy. Compared with similar alloys, rolled Ti₇₀Al₁₅Nb₁₀V₅ has lower density with balanced mechanical properties.