Ultrastrong duplex high-entropy alloy with 2 GPa cryogenic strength enabled by an accelerated martensitic transformation

Abstract

The existing deformation-induced martensitic transformation mostly focuses on overcoming the trade-off of cryogenic strength-ductility; however, an enhancement of cryogenic strength further is still challenging. We present a concept to yield a cryogenic strength of 2 GPa in a duplex V10Cr10Co30Fe50 alloy. We adopt a thermodynamic calculation to reduce the stability of metastable face-centered-cubic (FCC) matrix, significantly promoting the martensitic transformation. In conjunction with the chemically driven promotion, the duplex structure including athermal body-centered-cubic (BCC) martensite enables mechanical strain partitioning to accelerate the transformation further. This finding could bean appropriate design strategy to develop new ultrastrong alloys for cryogenic applications. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.