MECHANICAL-PROPERTIES AND 95-DEGREES-C AGING CHARACTERISTICS OF ZIRCON-REINFORCED ZN-4AL-3CU ALLOY

Authors
Citation
Bj. Li et Cg. Chao, MECHANICAL-PROPERTIES AND 95-DEGREES-C AGING CHARACTERISTICS OF ZIRCON-REINFORCED ZN-4AL-3CU ALLOY, Metallurgical and materials transactions. A, Physical metallurgy andmaterials science, 27(3), 1996, pp. 809-818
Citations number
24
Categorie Soggetti
Metallurgy & Metallurigical Engineering","Material Science
ISSN journal
10735623
Volume
27
Issue
3
Year of publication
1996
Pages
809 - 818
Database
ISI
SICI code
1073-5623(1996)27:3<809:MA9ACO>2.0.ZU;2-E
Abstract
A process for preparing zinc alloy castings containing dispersions of zircon particles is described. Composites were prepared by stirring zi rcon particles in Zn-4Al-3Cu (ZAS) alloy melts and subsequently castin g these melts in permanent molds. It was found that additions of zirco n resulted in an increase in the sliding wear resistance and in the pr oportional limit in compression. The aging characteristics of the ZAS alloy have also been investigated by hardness tests, dilatometry techn ique, and transmission electron microscopy observations. There are two kinds of precipitates that occur during the aging process. The alpha- phase precipitates from the eta phase in the early stage of aging and the copper-rich epsilon-phase precipitates from the eta phase in the l ater stage of aging. Therefore, there are two peaks in the hardening c urve caused by both alpha-phase and epsilon-phase precipitation. The a lpha-phase precipitation induces the dimensional shrinkage, and the co pper-rich epsilon phase precipitation results in dimensional expansion . Zircon particles existing in ZAS alloy reduce the maximum shrinkage from 353 X 10(-6) for the monolith to 167 x 10(-6) for the composite. Two groups of parallel alpha-phase plates had formed within the eta de ndrite during aging at 95 degrees C. The orientation relationship betw een the alpha phase and matrix was determined as [(1) over bar 101](<e ta)>//[l (1) over bar 0](alphaalpha), (11 (2) over bar 0)(eta)//(111)( alpha).