MICROSTRUCTURAL FORMATION MECHANISM OF SEMI-SOLID AZ91D ALLOY

作     者：W.M. Mao Z.S. Zhen H. T. Chen X. Y. Zhong 

作者机构：School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China 

出 版 物：《Acta Metallurgica Sinica(English Letters)》 (金属学报（英文版）)

年 卷 期：2005年第18卷第4期

页      面：539-546页

核心收录：

学科分类：0817[工学-化学工程与技术] 0806[工学-冶金工程] 08[工学] 0807[工学-动力工程及工程热物理] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0802[工学-机械工程] 0703[理学-化学] 0811[工学-控制科学与工程] 

基　　金：supported by the National Key Basic Research and Development Programme of China(No.G2000067202) National High Technical Reasearch and Development Programme of China(No.G2002AA336080) the National Natural Science Foundation of China(No.50374012) 

主　　题：AZ91D magnesium alloy electromagnetic stirring microstructure semi-solid 

摘      要：With the help of an electromagnetic stirring device and alloy melt quenching technology, the microstntcture of semi-solid AZqlD magnesium alloy slurry stirred by a rotationally electromagnetic fieM was studied and the experimental results are shown as the following. The primary α-Mg grains are refined obviously when the slurry is stirred by a rotational electromagnetic field during continuously cooling and they are eventually changed to fine rosette grains or spherical grains. If the above semi-solid slurty is further stirred isothermally for some time, much more spherical primary α-Mg grains can be obtained. If the melt is first cooled down to a given semi-solid temperature and then starts being stirred by the rotational electromagnetic field, the primary α-Mg dendrites will be large, and a longer time will be taken and a larger stirring power will be needed for the secondary army of the dendrites to be remelted on the roots to prepare an ideal semiolid slurry. Theoretical analysis indicates that the strong flow motion leads to a more even temperature field and a solute field and stronger man-made temperature fluctuation in the AZglD magnesium alloy melt so that the spherical primary α-Mg grains are increased in the slurry. Moreover, all the measures promoting the temperature fluctuation will be favorable to the formation of spherical primary α-Mg grains and all the factors increasing the arm＇s root remelting difficulty will be favorable to the formation of rosette-type primary α-Mg grains.