Revealing the decomposition mechanisms of dislocations and metastable α' phase and their effects on mechanical properties in a Ti-6Al-4V alloy. (30th April 2022)

• Record Type: Journal Article
• Authors: Su, Jinlong; Ji, Xiankun; Liu, Jin; Teng, Jie; Jiang, Fulin; Fu, Dingfa; Zhang, Hui
• Is Part Of: Journal of materials science & technology. Volume 107(2022)
• Page Start: 136
• Page End: 148
• Publication Date: 2022-04-30
• Subjects: Titanium alloy -- Heat treatment -- Microstructure -- Mechanical properties -- Dislocation; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2021.07.048
• Languages: English
• ISSNs: 1005-0302

Abstract

Abstract: The metastable α' phase and dislocation characteristics (e.g., density and constituents) are of vital importance for the mechanical responses of ( α + β ) titanium alloys. In this work, to reveal the in-depth decomposition mechanisms of dislocations and metastable α ' and their influences on mechanical properties in a Ti-6Al-4V ( α + β ) alloy, the thermal stability of different microstructures tailored by various cooling approaches were investigated utilizing scanning electron microscope, electron backscattered diffraction, transmission electron microscope and X-ray diffraction line profile analysis. The results showed that the initial characteristics of α ' and α laths and dislocation density were influenced by the cooling methods remarkably. The thermal stability of Ti-6Al-4V alloy increased with decreasing cooling rate. The improvement in thermal stability can be ascribed by the decrement in dislocations, partitioning of the alloying elements and grain orientations variation of the α ' lath and α phase. It is also found that the plastic strain accommodation of β → α ' transformation was dominated by dislocations. During stabilization annealing treatments, the, and dislocations simultaneously decomposed. The decomposition of dislocations and metastable α ' phase during various stabilization annealing and the particular twins and stacking faults microstructures formed during quenching have a great influence on the properties of the studied Ti-6Al-4V alloy. Graphical abstract: Image, graphical abstract