Study On Properties Of Mg₂Si/AM60 Prepared By In-situ And Its Rheo-diecasting Forming

Magnesium matrix composites can effectively improve its performance, it become the research hotspot at home and abroad. At present, the research focuse on particle-reinforced which the processing of method somewhat complicated and poor thermal stability. Because of simple process, excellent grain boundary combination and other advantages, the method of in-situ to prepare composites became the main object of study. In addition, die-casting is the main of Magnesium alloy forming process, the conventional high-pressure die-casting(HPDC) defects in multi-cavity type, easy to volume gas, non-heat-treated. Compared with those produced by HPDC and any other SSM processing techniques, the rheo-diecasting(RDC) process has been great developed for near-net shape components. This paper mainly include:Added the Si powder into AM60, Mg2Si/AM60 composites was prepared by mechanical stirring in-situ. Different contents of Si powder affect on materials and mechanical properties of Mg2Si/AM60 composites were studied, and identified the optimal dosage of Si. The Mg2Si/AM60 composites strengthening mechanism has been studied. The conclude show that Chinese characters type Mg2Si distributed in the microstructure. with the Si content increase, the hardness of composites was improved, strength will reach a peak and then decrease quickly, plasticity continued to decline.By studying the Mg2Si/AM60 composites with different parameters (load, Si mass fraction, sliding speed) on the friction and wear performance found that with the increase of Si content, Mg2Si/AM60 friction and wear properties was reinforced. With increase of Si contents, the wear mass of Mg2Si/AM60 composites continued to decrease. Mg2Si/AM60 composites can postpone the arrival of inflection point. Under the conditions of the various parameters, got a in-depth study on the process of wear mechanism.Semi-Solid slurry of Mg2Si/AM60 composites was prepared by mechanical stirring and studied different parameters (shear rate, shear time, shear temperature) affect on the microstructure of semi-solid slurry. It was found that the higher shear rate, the smaller globular solid particles, the shear time too short, dendrite can not completely broken, the shear time too long, solid particles would be grown, and some spherical particles would be deformated. Shear temperature get lower, solid fraction get more. At high shear temperature, liquid phase increased, a small parts of solid-phase started melting.Compared with HPDC, the microstructure and appearance of parts which produced by RDC, the microstructure of RDC was dense, low porosity and have a good surface. The reasons of generated of flash defects, reticular pattern defects, modulus viscous defects and other defects were studied.