Polymorphic transformation and elemental diffusional controlled phase spheroidization of eutectic VNbTiSi medium entropy alloy during heat treatment
Source abstract
Abstract
Microstructure evolution of a eutectic VNbTiSi medium entropy alloy (MEA) was systematically investigated during annealing heat treatment. Polymorphic transformation from β-(Nb, X) 5Si 3, a high-temperature metastable phase, to α- or γ-(Nb, X) 5Si 3 is revealed and is demonstrated to be closely related to element diffusion. There was mutual diffusion between V and Si, forming a diffusion transition, and the Ti diffusion promoted the formation of γ-(Nb, X) 5Si 3 mainly distributed at the grain boundary because of the Ti supersaturation in the BCC phase during solidification. Strong elemental diffusion promotes the formation of a thermal groove at the three junctions of sub-grain boundaries, contributing to the fast spheroidization of (Nb, X) 5Si 3 , while the termination migration dominates the subsequent coarsening stage. Polymorphic transformation of silicides brings in sub-grain boundaries or low angle grain boundaries (LAGBs), contributing to silicide refinement. As a result, the compressive strength at elevated temperatures is greatly improved due to the increasing volume fraction of (Nb, X) 5Si 3 after heat treatment.
Source: expertdata · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: High Entropy Alloys Studies · Intermetallics and Advanced Alloy Properties · High-Temperature Coating Behaviors
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
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