Study On AZ31Magnesium Alloy Cast-melting Surface Alloying In Al-Zn Alloy

Along with the continuous decrease of energy and increasingly pollution ofenvironment, people care about energy saving and emission reduction more and more,especially the mechanical lightweight. Magnesium alloys have advantages of low densityand high specific strength, many scholars pay more attention to study on them. Theproperties of wear resistance and corrosion resistant of the magnesium alloys are poor, andthis greatly limits the application of magnesium alloys. Recently, more scholars begin tostudy on improving the properties of the magnesium alloys to replace the steel.At present, there are many methods of magnesium surface alloying treatment, such aschemical conversion processing, anodic oxidation technology, microarc oxidation technology,laser surface treatment and so on. But all of these methods have disadvantages of complextechnology and expensive devices, some of these methods are harmful to human and theycan cause the pollution of environment.This paper uses the method of AZ31magnesium alloy surface alloying in semi-solidZn-Al alloys. AZ31magnesium alloy forms surface alloying layer with Al and Zn alloys.The abundant solid solutions and intermetallic compounds in the alloying layer can increasethe hardness of the surface of the AZ31magnesium alloy, and improve the property of wearresistance. Contrast with the conventional methods, the method used in this paper has theadvantages of simple procedure, shorten time and low cost, so it can greatly increase theeconomic benefit.This paper uses three kinds of alloy compositions, Zn, Zn-25Al, Zn-50Al, and thesealloys can successfully form surface alloying layer with AZ31magnesium alloy. This paperuses X-ray diffraction to analyses the phase of the alloying layer, and the results show thatthere are abundant intermetallic compounds of Mg-Al, Mg-Zn and Al-Zn. Analyze thedistribution of the elements in the alloying layer with the EDS, and the results show that thechange trend of each element is gentle and continuous. The results above also illustrate thatthe AZ31magnesium alloy and the semi-solid alloys occur reactions and mutual diffusion,and they can combine well.This paper also analyzes the microhardness of the AZ31magnesium alloy and alloyinglayer. From the results we know that the microhardness of the alloying layer is over100HV,and the microhardness of AZ31magnesium alloy is about50HV. The microhardness ofalloying layer is much higher than that of the AZ31magnesium alloy. Wear is one of the main failure forms of metal. This paper also studies the wearperformance of the alloying layer and AZ31magnesium alloy. This paper uses MG-200highspeed and high temperature frictional wear experiment machine to test the ware resistance inroom temperature, without any lubricant, and the load is100N, the wear trip is146.95m.Calculate the wear capacity through weighing the quality of the samples before and afterwear test. The results show that the wear capacity of the alloying layer is about one third ofthat of the AZ31magnesium alloy. The results demonstrate that the intermetallic compoundsin the alloying layer improve the wear resistance of AZ31magnesium alloy.