Study On Refinement And Spheroidization Of Silicon Phase In Al-Si Alloy Through The High Temperature Surface Friction

In recent years, using the friction stir weld technique for metal refinement, significantly improve the intensity of metal and plastic etc. At the present,it's more and more development point by researchers. In friction stir weld metal material is thinning of the joint action of heat-mechanical deformation severe of the matrix and the shear, the refinement of second phase carbide. This paper try to take advantage of the friction heat-mechanical joint action to Al-Si alloy phase of silicon refined and spheroidized. One of the sample before friction preheated processing to the friction surface deformation of thick layer.The paper mainly studies in different temperature frictional condition Al-Si alloy silicon in shape, size, silicon phase and the analysis of the causes of the refined and spheroidized, friction extrusion preliminary test.After high temperature friction test, The results show that both flake eutectic Si and coarse multi-angular primary Si particles in AlSi7, AlSil2 and AlSi30 friction surface layers were refined and spheroidized. the average diameter of Si particles were refined to 0.89μm,0.98μm,1.05μm. At the same time, the shape factor reached 0.79,0.71 and 0.67.Friction of high silicon alloy time AlSi30 temperature effect of friction surface silicon phase results show that with the extension of time, the friction surface details of silicon area rapidly in diameter to achieve minimum 3min,0.99μm, when 1.66μm maximum 30min, In the 3 min and anti-spheroidizing best when suddenly drops. inally globular factor in the very long time slowly rising.For high preheating temperature frictional AlSi30 alloy surface of silicon research result shows indicate that the average diameter is refined reached 0.71-0.87μm, average globular factor reached 0.69～0.74. Different load of high silicon alloy AlSi30 temperature effect of friction surface silicon in research results that surface discontinuity of refined district organization. From the lower multiples metallographic photos can see organization discontinuous. You can see from the high multiples metallographic photos the silicon phase particles smaller at the big press than to small press, but with the load increases the size of silicon no obviously changes.Besides, in order to discuss the application, this paper introduces a design method of extrusion, friction surface layer of thinning which formed by extrusion profiles and friction temperature will get the spheroidized organization. Using the principle and the preparation of particle reinforced composites, the results show that under the condition of appropriate parameters, extrusion profiles.To sum up, through Al-Si alloy surface high temperature frictional spheroidized and refinement in silicon preliminary research. This method of high temperature that friction material and structure is feasible, The effect is remarkable, thus provided a silicon is refined and new method.