Magnesium silicide intermetallic alloys

Journal Article · Mon Nov 01 00:00:00 EST 1993 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02646518· OSTI ID:5730582

Li, G H; Gill, H S; Varin, R A ^[1]

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1. Univ. of Waterloo, ON (Canada). Dept. of Mechanical Engineering

Methods of induction melting an ultra-low-density magnesium silicide (Mg[sub 2]Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg[sub 2]Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 [times] 10[sup 5] Pa), at a temperature close to but not exceeding 1,105 C [+-] 5 C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg[sub 2]Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg[sub 2]Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg[sub 2]Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg[sub 2]Si matrix were found in the Mg[sub 2]Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

• OSTI ID: 5730582
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 24:11; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
MAGNESIUM BASE ALLOYS
MELTING
MICROHARDNESS
MICROSTRUCTURE
SILICON ALLOYS
ALUMINIUM ADDITIONS
ANNEALING
BINARY ALLOY SYSTEMS
CHEMICAL COMPOSITION
CHROMIUM ADDITIONS
COBALT ADDITIONS
COPPER ADDITIONS
EXPERIMENTAL DATA
INTERMETALLIC COMPOUNDS
IRON ADDITIONS
MANGANESE ADDITIONS
NICKEL ADDITIONS
SAMPLE PREPARATION
SILVER ADDITIONS
ZINC ADDITIONS
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
COBALT ALLOYS
COPPER ALLOYS
DATA
HARDNESS
HEAT TREATMENTS
INFORMATION
IRON ALLOYS
MAGNESIUM ALLOYS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
NICKEL ALLOYS
NUMERICAL DATA
PHASE TRANSFORMATIONS
SILVER ALLOYS
ZINC ALLOYS
360101* - Metals & Alloys- Preparation & Fabrication
360102 - Metals & Alloys- Structure & Phase Studies
360103 - Metals & Alloys- Mechanical Properties