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pISSN : 1598-706X / eISSN : 2288-8381


(논문)연구논문

한국주조공학회지 (23권3호 130-136)

Microstructural Change in Rheocast AZ91D Magnesium Alloys with Stirring Rate and Isothermal Stirring Temperature

교반속도 및 등온교반온도에 따른 AZ91D 마그네슘합금 반응고 주조재의 미세조직 변화

Chang Dong Yim, Kwang Seon Shin*

Seoul National University, *Center for Advanced Aerospace Materials

Abstract

Rheocasting of AZ9 I D magnesium alloys yielded the microstructure consisted of the spherical primary particles in the matrix which is different from conventional casting. Rheocast ingots were produced under various processing conditions using batch- type rheocaster. Morphology of primary particles was changed from rosette-shape to spherical shape with increasing stirring rate (V\) and decreasing isothermal stirring temperature (T5). With increasing VS, more effective shearing between the particles occurred rather than the agglomeration and clustering, so the primary particle size decreased. But with decreasing TS, primary par- ticle size increased mainly due to sintering and partially Ostwald ripening. The sphericity of primary particles increased with increasing V, and decreasing Tb due to enhanced abrasion among the primary particles. The uniformity of primary particle size increased with increasing Vs and Th.

Keywords

Magnesium Alloy, Rheocasting, Stirring Rate, Stirring Temperature, Microstructure