Edge Dislocations Can Control Yield Strength in Refractory Body-Centered-Cubic High Entropy Alloys

Francesco Maresca; Chanho Lee; Rui Feng; Yi Chou; Tamas Ungar; Michael Widom; Ke An; John Poplawsky; Yi-Chia Chou; Peter Liaw; William Curtin

arXiv · 2008.11671

Edge Dislocations Can Control Yield Strength in Refractory Body-Centered-Cubic High Entropy Alloys

Francesco Maresca·Chanho Lee·Rui Feng·Yi Chou·Tamas Ungar·Michael Widom·Ke An·John Poplawsky·Yi-Chia Chou·Peter Liaw·William Curtin

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Abstract

Energy efficiency is motivating the search for new high-temperature metals. Some new body-centered-cubic random multicomponent "high entropy alloys (HEAs)" based on refractory elements (Cr-Mo-Nb-Ta-V-W-Hf-Ti-Zr) possess exceptional strengths at high temperatures but the physical origins of this outstanding behavior are not known. Here we show, using integrated neutron-diffraction (ND), high-resolution transmission electron microscopy (HRTEM), and theory, that the high strength and strength retention of a NbTaVTi alloy and a new high-strength/low-density CrMoNbV alloy are attributable to edge dislocations. This is surprising because plastic-flow in BCC elemental metals and dilute alloys is universally accepted to be controlled by screw dislocations. We use the insight and theory to perform a computationally-guided search over $10^7$ BCC HEAs and identify over $10^6$ possible ultra-strong high-temperature alloy compositions for future exploration.

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Francesco Maresca, Chanho Lee, Rui Feng, Yi Chou, Tamas Ungar, Michael Widom, Ke An, John Poplawsky, Yi-Chia Chou, Peter Liaw, William Curtin. 2020-08-26. Edge Dislocations Can Control Yield Strength in Refractory Body-Centered-Cubic High Entropy Alloys. https://arxiv.org/abs/2008.11671

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