AZ91합금의 조직과 시효특성에 미치는 Ca 및 Si의 영향 = Research Effects of Ca, Si on the Microstructure and Aging Characteristic of AZ91 Alloy

다국어 초록 (Multilingual Abstract)

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다국어 초록 (Multilingual Abstract)

The effects of calcium and silicon on microstructure and aging characteristics of AZ91 magnesium alloy during T5 treatment was investigated. The addition of 0.88% calcium or 0.25% silicon to AZ91 alloy made dendrite cell smaller. Especially, silicon is more effectively acted as refinement of the dendrite cell than calcium. It is due to that Mg_2Si precipitated at the dendrite cell boundary or in the matrix during T5 treatment of Si added AZ91 alloy retarded the growth of the secondary phase. In the mean while, without inducing the precipitates containing calcium, calcium was segregated mainly around secondary phase such as Mg_17Al_12 and partially dissolved in ternary eutectic (Mg-Al-Ca) structure. In the AZ91 alloy containing both silicon and calcium, more finely distributed Mg_2Si in matrix homogeneously and much finer microstructure were obtained than those containing silicon or calcium. Hence, An AZ91 containing both silicon and calcium was more effective to retarding the growth of the secondary phase than the other AZ91 alloy such as AZ91 alloy containing silicon or AZ91 alloy containing calcium.