Effect Of Modified Ceramic Nano-powders On Microstructure And Properties Of AZ91D

In recent years,the rapid development of magnesium alloy,with its good heat dissipation,good recovery,anti electromagnetic interference and shielding ability,magnesium alloy as a new type of green engineering materials.In the field of engineering application,magnesium alloy is the lightest metal structural material at present,and has wide application prospect in the field of aerospace,automobile industry,electronic communication industry and biological material.However,the chemical properties of magnesium alloys are very active,and they are easy to be corroded.So it is necessary to improve its corrosion resistance.This paper studied the the microstructure,mechanical properties and corrosion resistance of AZ91 D with different kinds of modified nano-powders(SiC,TiC,TiB2)and different mass fraction powders(0.05%,0.1%,0.2%,0.5%,1%)and different process(press method,pour over method,ultrasonic method),and discussed the mechanism and corrosion mechanism of modified nano-ceramic powders.The AZ91 D samples with different kinds of powders: on the microstructure,the size of the primary ?-Mg phase becomes smaller,the dendrites decrease or disappear,and the ? phase changes from the coarse skeleton to the small island or point.The most obvious refinement of AZ91 D with TiB2.The tensile strength and elongation of AZ91 D with TiB2 were the highest,which increased by 13.3% and 74.3%,respectively.On corrosion resistance,in 3.5% NaCl and alkaline solution,AZ91 D with TiC modified powder has the best corrosion resistance.The AZ91 D samples with different mass fraction powders:on the microstructure,the microstructure of AZ91 D is more and more refined with the addition of powder,and the microstructure of AZ91 D with the addition of 1.0%SiC powder is the best.On the mechanical properties,the elongation of AZ91 D with 0.5%SiC powder increased the maximum,increased by 47.1%.The tensile strength of AZ91 D with 1.0%SiC powder was the most significant,which increased by 12.8%.On corrosion resistance,in 3.5%NaCl solution,the corrosion resistance of samples with 1.0% SiC powder is the best.The AZ91 D prepared by adding 0.2%SiC modified powder with different adding process has different effects.On the microstructure,the grain size of the primary ?-Mg phase of the magnesium alloy prepared by press method is fine and uniform,and the grain refining effect is the most obvious.The tensile strength of the magnesium alloy prepared by press method is the largest,which is increased by 12.2%,and the hardness of the magnesium alloy prepared by the ultrasonic method is the biggest,which is increased by up to 7.3%.In the 3.5%NaCl solution and alkaline solution,the corrosion resistance of magnesium alloy prepared by pour over method is the best.