Chih Ming Lin
National Tsing Hua University, Taiwan
Title: Synthesis of a stable HCP-FCC mixture phase of the high-entropy superalloys Al0.15Co0.18Cr0.12Fe0.11Ni0.36Ti0.08 at high pressure
Biography
Biography: Chih Ming Lin
Abstract
High-entropy superalloys (HESA), Al0.15Co0.18Cr0.12Fe0.11Ni0.36Ti0.08, non-equimolar solid solutions of six elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys containing FCC γ matrix with localized dispersion of L12 γ' particles. Here, we report the high-pressure synthesis of a stable HCP-FCC mixture phase of the prototypical high-entropy superalloys Al0.15Co0.18Cr0.12Fe0.11Ni0.36Ti0.08. This martensitic transformation begins at 0.55 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial FCC γ structure. However, the behavior of Al0.15Co0.18Cr0.12Fe0.11Ni0.36Ti0.08 is unique in that the HCP phase is retained following decompression to ambient pressure, yielding a stable HCP-FCC mixture phase. This demonstrates a means of tuning the structures and properties of high-entropy superalloys in a manner not achievable by conventional processing techniques.