Effect of aging temperature on microstructure and mechanical properties of a novel Ti-6121 alloy

The effect of heat treatment on the microstructure and mechanical properties of a novel alpha + beta Ti-6.2Al-0.8V-2.25Mo-1.2Cr-0.5Si (wt%) alloy was investigated in this paper. Microstructure and crystalline structure of the alloys after different solution and aging treatments were identified by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that a multi-scale microstructure was possessed in the heat-treated samples, which was composed of equiaxed primary alpha (alpha p) phase and nano-scale acicular secondary alpha (alpha s). After 900 degrees C solution for 1 h and 550 degrees C aging for 6 h, the alloy exhibited the optimal combination of strength and ductility (the ultimate tensile strength of similar to 1387 MPa, the elongation of similar to 11 %). Furthermore, the combination mechanism of strength-ductility of the sample under this condition was investigated. The samples before and after tensile fracture were analyzed using transmission electron microscope (TEM) and electron back-scattered diffraction (EBSD). The results showed that a large propor-tion of nano-scale acicular alpha s phases precipitated from the beta matrix can effectively prevent the slip of dislocations and enhance the strength of the alloy. In addition, the multi-scale microstructure can create the strain partition, which can mediate the strain incompatibility between the alpha p and the transformed beta (beta T) to obtain an excellent combination of strength and ductility.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

The effect of heat treatment on a novel alpha + beta Ti-6.2Al-0.8V-2.25Mo-1.2Cr-0.5Si (wt%) alloy's microstructure and mechanical properties was investigated in this study. Different solution and aging treatments were conducted to identify the microstructure and crystalline structure of the alloys using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that a multi-scale microstructure containing equiaxed primary alpha (alpha p) phase and nano-scale acicular secondary alpha (alpha s) phase was achieved in the heat-treated samples. The optimal combination of strength and ductility was observed after specific solution and aging treatments.