High-strength Al0.2Co1.5CrFeNi1.5Ti high-entropy alloy produced by powder metallurgy and casting: A comparison of microstructures, mechanical and tribological properties

journal article in Web of Science

en

This work presents an in-depth comparison of the microstructural origins of high strength and high wear re-sistance in the Al0.2Co1.5CrFeNi1.5Ti high-entropy alloy produced by powder metallurgy (PM) and casting.The PM alloy microstructure is composed almost exclusively offine-grained FCC phase with minor, in-situformed TiC particles. The latter is responsible for a grain-boundary pinning effect and, consequently, the high-hardness of 712 HV was achieved allied with excellentflexural strength (2018 MPa) and elastic modulus of258 GPa. Its wear properties surpass those of the wear-resistant AISI 52100 steel under 1.2 N load. Despite thehigh strength properties of PM alloy, a ductile fracture behaviour was retained.In contrast, the cast alloy is composed of a coarse-grained dendritic microstructure of FCC matrix containing acomplex of intermetallic phases. Its tribological properties are superior to traditional AISI 52100 steel under allsliding conditions, exhibiting the best results among all tested materials. However, its elastic modulus (210 GPa)andflexural strength (1101 MPa), at a comparable hardness level (682 HV), were significantly lower whencompared to the PM counterpart. This stems from the intrinsic brittleness of the cast material, a consequence ofits complex microstructure, exhibiting pure cleavage-type fracture in several areas of the fracture surface.

This work presents an in-depth comparison of the microstructural origins of high strength and high wear re-sistance in the Al0.2Co1.5CrFeNi1.5Ti high-entropy alloy produced by powder metallurgy (PM) and casting.The PM alloy microstructure is composed almost exclusively offine-grained FCC phase with minor, in-situformed TiC particles. The latter is responsible for a grain-boundary pinning effect and, consequently, the high-hardness of 712 HV was achieved allied with excellentflexural strength (2018 MPa) and elastic modulus of258 GPa. Its wear properties surpass those of the wear-resistant AISI 52100 steel under 1.2 N load. Despite thehigh strength properties of PM alloy, a ductile fracture behaviour was retained.In contrast, the cast alloy is composed of a coarse-grained dendritic microstructure of FCC matrix containing acomplex of intermetallic phases. Its tribological properties are superior to traditional AISI 52100 steel under allsliding conditions, exhibiting the best results among all tested materials. However, its elastic modulus (210 GPa)andflexural strength (1101 MPa), at a comparable hardness level (682 HV), were significantly lower whencompared to the PM counterpart. This stems from the intrinsic brittleness of the cast material, a consequence ofits complex microstructure, exhibiting pure cleavage-type fracture in several areas of the fracture surface.

High–entropy alloys; Microstructure; Mechanical properties; Tribological properties; Powder metallurgy; Casting.

01.01.2020

Elsevier

ELSEVIER SCIENCE INC, 360 PARK AVE SOUTH, NEW YORK, USA, NY, 10010-1710

1044-5803

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