A Novel Technique for Preparation of Leaded Aluminium Alloys in Small Scale Industries

摘要

A foundry technique has been developed which mixes and casts immiscible metallic melts. On solidification casting possesses uniform dispersion of one constituent into another. In coming future it may be popular In small scale industries. This technique is suitable enough to disperse heavy or light dispersoid phase into metallic matrix though both are insoluble in each other in solid and liquid states and form two separate immiscible layers in liquid state. In the present research work leaded aluminium alloys have been prepared by this technique. This foundry technique is a modified version of impeller mixing and bottom discharge chill casting technique. In this technique, immiscible aluminium lead melts were mixed in two stages Under continuous falling temperature and metallic system was vigorously agitated during solidification. A nondendritic structure of leaded aluminium alloy was obtained on solidification, whose morphology depended on the casting parameters. A large number of cylindrical castings were prepared under various agitation speeds, stirring times and pouring temperatures. Composition of the matrix alloy varied from commercial aluminium to Al-2 to 3wt% Cu, Al-2 to 11 wt% Si alloy whereas lead content mixed upto 30wt%. A Leitz Panphot optical microscope was employed to examine the microstructure of as cast leaded aluminium alloys. The lead inducted as interdendritic or structurally independent discrete particles and it did not form any visible additional micro-constituent in the cast structure of the alloy investigated.