Study On The Technical Base Of Al/Al₂O₃ Composite's Thixoforming In Pseudo-Semi-Solid State

Al/Al₂O₃ composite has many good properties such as little density,high temperature resistant,abrasion resistant and thermal shock resistance, and so on. It was used in more and more fields. At present, its preparing technologies mainly contain powder sintering technology,melt infiltration technology,Aluminum alloy directly oxidizes at high temperature technology. Pseudo-semisolid state thixoforming technology that bases on powder metallurgy and semi-solid processing technique present a new method for Al/Al₂O₃ composite's preparation and processing.In this paper, two kinds of micro-powder that Al powder and Al₂O₃ powder whose surface had been treated were mixed uniformly, then compacted at room and high temperature, got Al/Al₂O₃ composite pseudo-semisolid state thixoforming billet. Did pseudo-semisolid state compaction test, got Al/Al₂O₃ composite mechanical behavior law, then, directed thixoforming technology parameters'choice. Heated the billet to pseudo-semisolid state temperature, heat retained for a moment, at this time Aluminum had all melted, Al₂O₃ remain kept solid state, the billet at this time still has definite intensity, held it into the die impression that had been preheated, formed on 2000KN press machine. This paper chose cup shell as forming target, did a series of performance tests and structure observations on the shaped cup shell.In this paper, the Al/Al₂O₃ composite made by pseudo-semisolid state Thixoforming technology, was shaped very well, micro structure was uniform, performance on every hand at least reached the same material got by different means. Especially, its relative density reached over 95.5%, the biggest bend strength reached 624.63MPa,and the highest Vickers-hardness reached 647MP. In this paper's test it notes the way that prepares Al/Al₂O₃ composite using pseudo-semisolid state thixoforming technology is feasible. The thixoforming technology has well progress foreground .