Research On Microstructure And Mechanical Properties Of Mg₉₇Zn₁Y₂Alloy

In order to save materials and energy, the study and development on light castings has been an important research field and developing direction. Magnesium alloys have low density, high specific strength and specific stiffness, etc. So magnesium alloys have been widely used to reduce the car in automotive industry, it also becomes a focus in the field of material science. Despite of the growing interest in magnesium alloys, very little data exist on their friction and wear behavior. In this paper we studied the microstructure and mechanical properties of the alloys by melt-spun and traditional casting methods, especially friction and wear characteristics of the alloys by traditional casting methods.It has practical value on industrial production, and also will offer some theoretical foundations for expanding applications of magnesium alloys.At first, the ingredient and the atomic proportion of the melt-spun and casting alloys were determined by EDS and the XRD analysis, magnesium, zinc and yttrium three kinds of element atomic proportion approximately close to97:1:2, it is identical with designing.and then the microstructure was studied. The phase analysis indicated that, it consists of the substrate a-Mg and strengthened Mg12YZn.The melt-spun alloy was annealed at different temperatures, the microstructure and mechanical properties of alloys with different temperatures were investigated, the microstructure of the alloys were refined obviously at room temperature, were coagulated with increasing annealing temperature. The biggest hardness was131Hv at300℃for annealing.The ultimate tensile strength, yield strength and elongation to failure of the Mg97Zn1Y2and AZ91alloys at different test temperatures were obtained. By means of SEM, observations on fracture surfaces were carried out. The tensile properties of the Mg97Zn1Y2alloys were better than AZ91alloys, and Mg97Zn1Y2alloys still have good tensile properties at250℃. Simultaneously the explanation of strengthened mechanism of the alloys was made, and then the influence of experiment temperature on the mechanics performance and break characteristic was analyzed.Finally, in contrast with that of the AZ91magnesium alloy, the friction and wear performance of Mg97Zn1Y2alloys were studied. The transition of Mg97Zn1Y2alloys from mild wear to severe wear was later than AZ91alloys. The wear mass loss of two alloys increase with increasing load, but the wear mass loss of AZ91alloys were lower than Mg97Zn1Y2alloys at low load, but that of Mg97Zn1Y2alloys were almost constant under320N. The friction coefficients of the Mg97Zn1Y2alloys were lower than that of AZ91alloys. By means of SEM, observations on wear surfaces, the cross sections were carried out. The bulk temperature and the local flash temperature ware calculated by some formulas, At the same loads, the temperature of Mg97Zn1Y2alloys were lower than that of AZ91alloys, and then the difference of wear mechanism and performance of two alloys were discussed. At last we got the conclusion that tradition casting Mg97Zn1Y2alloys have the broader application prospect.