Number： 01099014 Download Name： 蔣志德 Titles： Assistant Professor Author： LEE Shyong、Chiang Chih-te、 HSU Chang-chuan Paper name： Inter-granular liquid phase aiding grain boundary sliding in superplastic deformation of fine-grained ZK60 Mg alloy Name of activity： Transactions of Nonferrous Metals Society of Keywords： Mg alloy; inter-granular phase; grain boundary sliding; supreplastic deformation Abstract： For 7475 Al alloy, there were micrographs showing filaments or whiskers formation during the separation stage of superplastic elongation. This indicates the presence of liquid phase which accommodates grain boundary sliding to reach superplasticity. On the other hand, there is no such phenomenon reported regarding Mg alloy in literatures. Scanning electron microscopic (SEM) fractography exceptionally exhibits a mark of grain boundary sliding and its accommodating mechanism of inter-granular liquid phase. Under the testing conditions of 642% superplastic elongation and exhibits fluffy appearance on the fractured surface. For other specimens showing less superplasticily, their fractured surfaces exhibit partial fluffy appearance.