Study On Forming Technology,Microstructure And Properties Of Magnesium Alloy Manufactured By Selective Laser Melting

As the lightest structural material,magnesium alloy has excellent biocompatibility,degradability,human-like elastic modulus and mechanical properties,and has great potential in the application of orthopaedic materials.Laser selective melting technology can process complex parts rapidly with high dimensional accuracy and no subsequent process requirements.It has a broad prospect in the field of magnesium alloy additive manufacturing.Mg-Al-Zn alloy,Mg-Al-Y alloy and Mg-Al-Cu alloy,three kinds of magnesium alloy samples were fabricated by laser selective melting in this paper.By observing the pore distribution,Porosity,XRD,SEM,EDS,microhardness test,compression test and fracture morphology of magnesium alloy,the influence of laser selective melting on the forming technology,microstructure and properties of porous magnesium alloy was studied.The single-channel scanning experiment was carried out on Mg-Al-Zn alloy and the samples were prepared.It was found that laser power and defocusing amount had a significant influence on the porosity and microhardness of Mg-Al-Zn alloy.The samples with the best molding quality were prepared.The research on Mg-Al-Zn mainly focuses on the influence of aser power and scanning spacing on porous and solid magnesium alloys.When laser power was 120 W and hatch spacing was 0.5 mm,the sample of Mg-Al-Zn alloy with a density up to 96.6%were prepared.In a single pool,from the bottom to the top of the pool,the grains changed from small cellular grains of 1?2 to dendrite grains of 8?10 ?m.Under the same laser power,the microhardness of the solid is higher than that of the porous structure.The improvement of microhardness is mainly attributed to grain refinement and solid solution strengthening.The fracture mode of alloy was a mixed fracture mode.For Mg-Al-Y alloy,porous samples with 0%,0.5%,1%,3%and 5%Y2O3 content were studied respectively.It was found that Y element contributes to grain refinement of magnesium alloy.In terms of mechanical properties,Y element plays a significant role in enhancing microhardness,and the compressive strength of porous mg-al-y alloy meets the requirement of dense bone.The mixed fracture mode changed from mixed fracture mode to ductile fracture.For Mg-Al-Cu alloy,porous samples with 0%,0.5%,1%,2%and 3%Cu content were studied respectively.It is found that Cu contributes to grain refinement of magnesium alloys.In terms of mechanical properties,Cu element plays a significant role in enhancing compression properties,and the compressive strength of porous mg-al-cu alloy meets the requirement of dense bone.The porous Mg-Al-Cu alloy mainly exhibits ductile fracture.