A Research On Carbonaceous Gas Inoculation Of Mg-Al Alloy

Currently,the low pressure and gravity Mg-Al alloy castings for aeronautical and space applications are still produced with magnesite inoculation that is notorious for its“manual control and batch based in nature,poor working condition and repeatability,heavy pollution to melt.Therefore,it is necessary to explore a substitutive technique that suit to the needs of Mg industry of 21st century.Previously,a gaseous inoculation of Mg-Al alloy was successfully explored,which is digitally controllable,environment friendly and can be processed continuous in nature.In this paper,the thermodynamics of CO₂,CH₄,C₂H₂ inoculative reactions to Al containing Mg melt was analyzed,the inoculation effects of CO₂,CH₄,C₂H₂ gases to AM60B alloy and there decay were comparatively studied by experiment.The effects of inoculation on microstructure,mechanical properties at room temperature were investigated.Following results are achieved.?1?There is sufficient thermodynamic driving force for CO₂,CH₄,C₂H₂ gases to react with melt to form Al₄C₃,the potential heterogeneous nuclei for AM60B solidification,which is made evidence by energy spectrum analysis.?2?10 min.after inoculation with at 760?,CO₂ produces the best rain refinement,followed by C₂H₂ and CH₄.The average grain sizes of the AM60B were refined from376?m of untreated aloy to 91?m,126?m and 130?m,respectively.?3?Inoculated with CO₂,CH₄ and C₂H₂,the hardness of AM60B alloy increase from 55.9 HV of unrefined alloy to 62.1 HV,59.5 HV and 60.2HV respectively.The tensile strength increase from 152.72MPa of untreated alloy to 190.15 MPa,168.89MPa and 178.08 MPa,respectively.The elongations increase from 4.9%of unrefined al oy to 7.6%?6.9%?7.1%,respectively.?4?With holding time post inoculation,the average grain size of AM60B inoculated by CO₂ decreases and then increased at 30min,and that inoculated by CH₄increased rapidly with the holding time,while that inoculated by C₂H₂ decreased first and then increases again at 30min.