Study On Melt Treatment Process Of SiC_p/Al Composite

Low densification and SiC_paggregation are main defects which exit in SiC_p/Alcomposite that fabricated with the semi-solid stirring technology. In order to eliminatethis two defects the treatment that electromagnetic stirring in vacuum condition isemployed to10vol%SiC_p/Al composite melt in this paper. The effect of parameterduring the treatment of SiC_p/Al composite melt such as electromagnetic stirring, thevacuum of furnace and the temperature of melt on low densification and SiC_paggregation is researched by means of theoretical calculation and probe trail. The besttechnology employed to treatment of SiC_p/Al melt is worked out at last.It can be inferred from theoretical calculation that during the treatment of SiC_p/Alcomposite melt the higher vacuum degree we employed in the treatment the less timebubbles which exist in SiC_p/Al composite melt need to float to surface of compositemelt. If the radius of a bubble which exits in composite melt less than1.68m, thisbubble can’t float to surface of composite melt for the reason that the upward forcesubjected to the bubble less than0. In the condition of electromagnetic stirring is10kw,the floating of the bubble whose radius longer than20.94mm have little relation witheffect of electromagnetic stirring, for the reason that the upward force subjected to thebubble greater than the force of electromagnetic stirring.It can be inferred from result of experiment that during the treatment of SiC_p/Alcomposite melt the effect of electromagnetic stirring is able to eliminate thephenomenon of SiC_paggregation that obviously improve the uniformity of SiC_pwhichdistribute in Al matrix. The condition of vacuum is important to the improvement ofSiC_p/Al composite’s densification. The higher degree of vacuum we employed in thetreatment the denser SiC_p/Al composite we can get, but the floating of bubbles whichexist in the SiC_p/Al composite melt carrys SiC_pto the surface of composite melt in thecondition of vacuum which decrease the SiC_pcontent of SiC_p/Al composite, the higherdegree of vacuum we employed in the treatment the more SiC_pwill be expelled fromcomposite melt. Both the densification and the SiC_pcontent’s stability of SiC_p/Alcomposite are affected by the temperature of melt, we can improve the densification ofSiC_p/Al composite by means of carrying out the treatment to melt within lowtemperature range(680℃~550℃) of SiC_p/Al composite melt, meanwhile, the SiC_pcontent’s stability of SiC_p/Al composite can be kept within certain range. Taking allfactor during the treatment of SiC_p/Al melt into account, carrying out the treatment ofSiC_p/Al composite melt within high degree of vacuum(higher than2KPa) and lowtemperature range(680℃~550℃) of SiC_p/Al composite melt is the best technology employed to treatment of SiC_p/Al melt. Employing best technology to the treatment of10vol.%SiC_p/Al composite melt we can obtain better SiC_p/Al composite thedensification of which is98.91%and SiC_pcontent of which is stable during8%~10%.The mechanical properties(T6) of SiC_p/Al composite which treated with the besttechnology can be list as follow: the tensile strength is338MPa which increases39.1%;the microhardness is214HV which increases32.9%; the modulus of elasticity is92GPawhich increase10.2%; the elongation is lower than1%which still very poor.