Effects Of Al-Mn Master Alloys Addition On The Microstructures And Mechanical Properties At High Temperture Of Mg-Al-Mn Systerm Alloys

With the advantages of light-weight,high strength/weight ratio,superior damping capacity,recyclability et al,the application of magnesium alloys is increasing rapidly in automobiles industry.AM60 magnesium alloy is a kind of broadly used casting magnesium alloys because of its low manufacturing cost and good processing property.However,the poor high-temperature performance impedes its application scope,so how to improve its high-temperature performance has became a subject that interested many magnesium alloy researchers.In this study two different ingredients of Al-Mn master alloys are first prepared,then adding the prepared master alloys in molten magnesium separately to prepare AM60 A and AM61 A magnesium alloys.The microstructures and phase components of prepared magnesium alloys were investigated using Optical Microscope(OM),Scanning Electron Microscopy(SEM)with Energy Dispersive Spectrometer(EDS),the effects of adding Al-Mn master alloys on the mechanical properties of AM alloys were investigated by the tensile test of prepared magnesium alloys at room and high temperture,the mechanism of improving the high-temperature performance of adding Al-Mn master alloys of AM alloys was investigated by analyzing the microstmctures of solution treatment and ageing treatment of prepared magnesium alloys.The results show that adding Al-Mn master alloys can improve the morpnology and distribution of β-Mg17Al12 effectively in the microstructure of AM alloys,reduce the amount and size of bulky eutectic β-Mg17Al12,increase the amount of granularβ-Mg17Al12.So the mechanical properties of magnesium alloys at room temperature have been improved obviously.Meanwhile,quicken the cooling rate can refine the grain size of magnesium alloys.Al-Mn is a kind of high-temperature phase with thermal stability,it can be unchanged after 45 hours heat preservation at 450℃,so adding Al-Mnmaster alloys can improve high-temperature strength of AM alloys obviously.AM alloys can form many small granular high-temperature phase while the ageing treatment,is good for the improvement of the performance at high temperture strength of AM alloys.AM61 A alloy contains more Al-Mn organization,so it has the best high-temperature strength.