Nanotwin's formation and growth in an AlCoCuFeNi high-entropy alloy

Nanotwins were formed in the AlCoCuFeNi high-entropy alloy produced by melt-spinning. The Cu-rich nanotwins have a face-centered-cubic (FCC) structure diffused in the ordered body-centered-cubic (B2) matrix. The nanotwins decompose from the matrix with the K-S crystallographic relationship: {111}(FCC) parallel to (110}(B2) and < 110 >(FCC) parallel to < 111 > B-2. After annealing, the spherical nanotwins grow into rodlike grains. The growth direction is parallel to the {111} twin planes of the FCC phase. The hardness and elastic modulus change with the twin size, which is tested by nanoindentation. This study deepens the fundamental understanding of the phase transition in HEAs. (C) 2015 Elsevier Ltd. All rights reserved.