Study On Microstructure And Properties Of Mg-xAl-yZn-zSi Alloy Containing Ca And Sb

In this paper was based on Mg-Al-Zn-Si alloy as the foundation.The differecnt content of Al, Zn, Siwas studied on the cast Mg-Al-Zn-Si alloy microstructure and properties influence. At the same time, alone with Sb, Ca elementon the microstructure and properties of Mg-Al-Zn-Si alloys were investigated, and compound added Ca, Sb elementon the microstructure and properties of Mg-Al-Zn-Si alloys were investigated, and explore the mechanism of Mg2 Si particles refinement and the enhanced law of the alloys. Experimental results are shown as follows:The content of Al, Zn, Si has influenced on the shape, size and distribution of Mg2 Si phase in the Mg-Al-Zn-Si alloy. In the Mg-x(8,12)Al-8Zn-z(1,2,4)Si alloy and Mg-x(8,12)Al-12Zn-z(1,2,4)Si alloy, as the content of Si increased, the feature of the Mg2 Si phase in the alloy changed from Chinese character or block into a skeleton. When the content of Si is 2wt% in Mg-8Al-8Zn-z(1,2,4)Si alloy, the Mg2 Si particles are small, the tensile mechanical properties of the alloy reached the maximum at room temperature and high temperature. When the content of Si is 1wt% in Mg-12Al-8Zn-z(1,2,4)Si alloy, the Mg2 Si phases are small clumps, the tensile mechanical properties of the alloy reached the maximum at room temperature and high temperature. When the content of Si is 2wt% in Mg-8Al-12Zn-z(1,2,4)Si alloy, the Mg2 Si particles are smaller and have a uniform distribution, the tensile mechanical properties of the alloy reached the maximum at room temperature and high temperature. When the content of Si is 2wt% in Mg-12Al-12Zn-z(1,2,4)Si alloy, the Mg2 Si particles present like small block and rod, the tensile mechanical properties of the alloy reached the maximum at room temperature and high temperature.When add trace amount of Sb in the Mg-x(8,12)Al-12Zn-2Si alloy, it generated Mg3Sb2 phase, as the content of Sb increased, the Mg2 Si particles become smaller, and when the content of Sb exceeds a certain value, the Mg2 Si particles become bulky. As the content of Sb increase, tensile strength, yield strength and elongation of the alloy at room temperature and high temperature are all reduce after a first increased.When add a certain amount of Ca in the Mg-x(8,12)Al-12Zn-2Si alloy, it generated CaSi2 phase, and made the Mg2 Si particles in the alloy changed from Chinese character into block. The top end of the Mg2 Si particles caused the germination and extensions of a crack, and reduced the tensile strength and yield strength of the alloy. When the content of Ca is 1wt% in Mg-8Al-12Zn-2Si alloy, the Mg2 Si particles are smaller and have a uniform distribution, the tensile mechanical properties of the alloy reach the best. When the content of Ca is 0.5wt% in Mg-12Al-12Zn-2Si alloy, the Mg2 Si particles are rounded corners, the alloy have an excellent tensile mechanical properties.When add 0.5wt%Ca and a certain amount of Sb in the Mg-12Al-12Zn-2Si alloy at the same time, it can improve the shape, size and distribution of Mg2 Si particles in the alloy, and the net structure of β-Mg17Al12 phase become wilder. When the content of Ca is 0.5wt% and the content of Sb is 0.8wt%, the Mg2 Si phase become bulk in the alloy and have a diffuse distributed, and the tensile mechanical properties of the alloy reached the maximum at room temperature and 150℃ high temperature.