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Achieving ultrahigh strength in a high entropy alloy via high density of hierarchical nanoprecipitates

Author: Date:2018-12-10 Source:

Speaker: Dr. Zhiqiang Fu

Affiliation: University of California, Irvine

Date: Dec. 27th (Thursday), 2018

Time: 10:30 - 11:30 AM

Contact: Prof. Zhaoping Lu (luzp@ustb.edu.cn)

Location: 353 Main Building, USTB

Abstract: High entropy alloys (HEAs) are a class of metallic materials that have revolutionized alloy design. They are known for their high compressive strengths, often greater than 1 GPa; however, the tensile strengths of most reported HEAs are limited. We report a strategy for the design and fabrication of HEAs that can achieve ultrahigh tensile strengths. The proposed strategy involves the introduction of a high density of hierarchical nanoprecipitates. To establish the validity of this strategy, we designed and fabricated a bulk Fe25Co25Ni25Al10Ti15 HEA to consist of a principal face centered cubic phase containing hierarchical intragranular nanoprecipitates. Our results show that precipitation strengthening, as one of the main strengthening mechanisms, contributes to a tensile yield strength of ~1.86 GPa and an ultimate tensile strength of ~2.52 GPa at room temperature, which heretofore represents the highest strength reported for an HEA with an appreciable failure strain of ~5.

Speaker’s short biography: He has published 37 papers in Science Advances, Acta Materialia, Scripta Materialia, and Materials Science & Engineering A.