Design and characterization of a novel MgAlZnCuMn low melting point light weight high entropy alloy (LMLW-HEA). (December 2022)

• Record Type: Journal Article
• Authors: Sadeghi, Mohsen; Niroumand, Behzad
• Is Part Of: Intermetallics. Volume 151(2022)
• Publication Date: 2022-12
• Subjects: High entropy alloy (HEA) -- Lightweight -- Low melting point -- Intermetallic compound -- Ordered solid solution -- Multi principle element alloy (MPEA); Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2022.107658
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: Development of high-entropy alloys (HEAs) is one of the remarkable advancements in the progress of new materials. In recent years, continuous efforts have been made to design light weight high-entropy alloys (LWHEAs) with suitable microstructure and superior properties. This paper reports the preliminary results of a study aimed at design and development of a new low melting point LWHEA (LMLW-HEA) based on AlMgZnCuMn alloy system without excessive intermetallic compounds formation. In this research, first, the initial chemical composition of the alloy was designed according to thermodynamic parameters, and then the alloy was melted in a resistance electric furnace. Since the thermodynamic indicators have been defined based on alloys containing 3d transition elements, formation of binary intermetallic compounds was predicted with the help of Midema model. To investigate the effects of cooling rate and heat treatment on the structure of the designed alloy, the molten alloy was poured into two different molds made of silica sand and steel, and both as cast samples were also heat treated. Microstructural features, mechanical properties and thermal stability of the samples were then examined. Density of the samples was measured to be less than 3.4 gr/cm 3 which was very close to the theoretical density of the alloy. Structures of all the samples were complex and multi-phase and contained intermetallic (ordered solid solution) binary and ternary compounds including Mg7 Zn3, MgZn2, Cu2 Mg, Al2 Cu, Mg32 (Al, Zn)49, Mg32 Cu7 Al47, Al25 Mg37.5 Zn37.5, and CuMgZn phases. The designed alloy was brittle under all the processing conditions. Compressive strength of the alloy reached to about 95 MPa, and its hardness was in the range of 110–120 HV. Oxidation resistance of the alloy was evaluated at a temperature about 30 °C below its solidus temperature and no weight change was observed in the sample after 14 h. It is suggested that the designed alloy is a suitable candidate for high temperature applications not involving impact or cyclic loading. Highlights: A new AlMgZnCuMn low melting point light weight HEA (<3.4 gr/Cm 3 ) was developed. Effects of cooling rate and heat treatment on the structure of the alloy were studied. Microstructure of the alloy was stable up to vicinity of its solidus temperature. Compressive strength of 95 MPa and hardness of about 120 HV were achieved. No weight change due to oxidation was recorded after 14 h at 500 °C.