PRECIPITATION BEHAVIOR OF AZ91 MAGNESIUM ALLOYS WITH DIFFERENT La CONTENTS
ZHANG Jinling1,2,3, FENG Zhiyong1, HU Lanqing1,2,3,WANG Shebin1,2,3, XU Bingshe1,2,3
1. Taiyuan University of Technology, College of Material Science and Technology, Taiyuan 030024
2. Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan 030024
3. Shanxi Research Center of Advanced Materials Science and Technology,Taiyuan 030024
Cite this article:
ZHANG Jinling1,2,3, FENG Zhiyong1, HU Lanqing1,2,3,WANG Shebin1,2,3, XU Bingshe1,2,3. PRECIPITATION BEHAVIOR OF AZ91 MAGNESIUM ALLOYS WITH DIFFERENT La CONTENTS. Acta Metall Sin, 2012, 48(5): 607-614.
Abstract The changes of microhardness, microstructures and precipitation phase morphologies of as--cast and aged AZ91 alloys with different La were characterized by TEM, OM, SEM and Vickers. The influences of discontinuous β phase and Al11La3 on AZ91 magnesium alloy were discussed and the diffusion coefficient of Al atom in the aging process was calculated. The results showed that the alloy with 0.16%La aged at 170 ℃ for 24 h has the largest hardness (138 HV). By extending aging time and adding La element, the discontinuous precipitation phases was transformed into continuous lath--sharped phases and the diffusion coefficient of Al atom was decreased, the volume and distribution of β phase were changed. During the process of heat treatment, the topography of Al11La3 in grain boundary was not changed, but the anchoring effect of Al11La3 restricted the growth of β phase. By controlling the content of La and parameters of aging treatment, the volume and size of β phase were changed, in the mean time the strengthening and toughness properties of alloys can been improved effectively.
