Formation mechanism of ultrafine α+β structure in Ti-6Al-4V alloy during β→αm→α+β continuous phase transformation

Document Type

Journal Article

Publication Title

Scripta Materialia

Volume

246

Publisher

Elsevier

School

School of Engineering / Centre for Advanced Materials and Manufacturing

Funders

National Natural Science Foundation of China / Natural Science Foundation of Shanghai / Foundation of Xi'an Key Laboratory of High-Performance Titanium Alloy

Comments

Hu, J., Jiang, Y., Yang, Y., Xing, H., Han, F., Zhou, G., . . . Huang, A. (2024). Formation mechanism of ultrafine α+β structure in Ti-6Al-4V alloy during β→αm→α+β continuous phase transformation. Scripta Materialia, 246, article 116066. https://doi.org/10.1016/j.scriptamat.2024.116066

Abstract

Although massive transformation has been increasingly observed in titanium alloys, the decomposition mechanism of the massive transformation product (am) is still unclear. Here, the B am a+B continuous phase transformation in Ti-6Al-4V alloy during cooling was studied. We found that massive transformation occurs at a moderate cooling rate below 291.5 °C/s, forming irregular featureless am. The thermodynamically unstable am is supersaturated with B stabilizers, and it tends to decompose into ultrafine a+B structure during the continuous cooling at ever-lower cooling rates and temperatures. In the initial stage of am decomposition, misfit dislocations appear as a predecessor and split am into strips. Accompanied by the elemental redistribution, misfit dislocations are accommodated and replaced by B phase. Both the formation and decomposition of am follow the typical Burgers orientation relationship.

DOI

10.1016/j.scriptamat.2024.116066

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