Microstructure evolution of α′ and α″ phase and mechanical properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy

doi:10.13251/j.issn.0254-6051.2023.03.035

Abstract

Abstract: Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy was subjected to solution and aging treatment. Effects of solution and aging on microstructure evolution of α′ phase and α′′ phase and mechanical properties of the alloy were analyzed by means of optical microscope, scanning electron microscope, XRD diffractometer, tensile test and impact property test. The results show that the size of primary α phase becomes smaller and tends to be equiaxed in the microstructure after solution treatment, and the smaller primary α phase dissolves and disappears, and the β transformation microstructure becomes insignificant. A large number of α_s phases are precipitated in the microstructure after aging, and the β transformation microstructure is more obvious. After solution treatment, the microstructure consists of α+α′+α″ phase. After aging treatment, the microstructure consists of α phase and β phase. After solution treatment, the tensile strength of the alloy is 1336 MPa, the yield strength is 1070 MPa, the elongation is 6%, the section shrinkage is 22%, and the impact absorbed energy is 16 J. After aging treatment, the strength of the bar increases with the increase of aging temperature, and the plastic trend is opposite, the impact toughness is almost unchanged. The tensile and impact fracture morphologies of the alloy after solution treatment are composed of dimples, which is a typical ductile fracture. After aging treatment, the micromorphologies of the tensile and impact fracture have obvious ups and downs. With the increase of aging temperature, the size and number of dimples decrease, and tear edges and voids appear. The fracture type has a tendency to brittle fracture, but it is still dominated by ductile fracture.

Key words: α′ and α″ phases, organizational evolution, mechanical properties, fracture morphology

CLC Number:

TG156.1

Yue Xu, Zhang Mingyu, Tong Xiaole, Qiao Enli, Zhang Qi, Yang Jialuo, Ye Hongchuan. Microstructure evolution of α′ and α″ phase and mechanical properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy[J]. Heat Treatment of Metals, 2023, 48(3): 215-220.

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