Phase transitions in additively manufactured high-entropy alloy Cr10Mn10Fe60Co10Ni10 …

Shock compression of an additively manufactured high-entropy alloy, Cr10Mn10Fe60Co10Ni10, is investigated via gas-gun plate impact. The postmortem sample shocked to 11.3 GPa is characterized with electron back-scattered diffraction and transmission electron microscopy; two phase transitions are observed, the face-centered cubic (FCC) to hexagonal close-packed (HCP) transition, and the FCC to body-centered cubic (BCC) transition. The HCP and BCC phases with different variants are observed following specific orientation relationships with the FCC matrix. The phase transitions are strongly affected by elemental segregation during the additive manufacture (the HCP and BCC phases are absent in the Mn and Ni enriched areas), and one possible reason is the increase of local stacking fault energy caused by the Mn and Ni enrichment.