The strain rate and temperature dependence of microstructural evolution of Ti–15Mo–5Zr–3Al alloy
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A compressive split-Hopkinson pressure bar apparatus and transmission electron microscopy (TEM) are used to investigate the deformation behaviour and microstructural evolution of Ti–15Mo–5Zr–3Al alloy deformed at strain rates ranging from 8 × 102 s−1 to 8 × 103 s−1 and temperatures between 25 °C and 900 °C. In general, it is observed that the flow stress increases with increasing strain rate, but decreases with increasing temperature. The microstructural observations reveal that the strengthening effect evident in the deformed alloy is a result, primarily, of dislocations and the formation of α phase. The dislocation density increases with increasing strain rate, but decreases with increasing temperature. Additionally, the square root of the dislocation density varies linearly with the flow stress. The amount of α phase increases with increasing temperature below the β transus temperature. The maximum amount of α phase is formed at a temperature of 700 °C and results in the minimum fracture strain under the current loading conditions.
KeywordsDislocation Density Flow Stress High Strain Rate Deformation Temperature Fracture Strain
The authors gratefully acknowledge the financial support provided to this study by the National Science Council (NSC) of Taiwan under contract No. NSC-93-2212-E006-076. Particular appreciation is also extended to Kobe Steel Ltd., Japan, for their supply of the Ti–15Mo–5Zr–3Al alloy bars.
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