A STUDY OF THE KINETICS OF OXIDE FORMATION ON SILICA INCLUSIONS IN MOLTEN ALUMINIUM-MAGNESIUM ALLOY AND ITS EFFECT ON MECHANICAL PROPERTIES

Abstract

siltea particles when they are dispersed in molten Al -Mg alloy for . different lenghts of time and it has bye n confirmed by x-ray analysis Kinetics of the oxide formed bare been analysed on the bests of growth exponent, a*- Theoretical models suggest that the growth exponent greater that 0*5 will Indicate the diffusion of i l or Mg in the molt as the slowest process and if It is equal to 0,5 then diffusion of Al or Mg in the oxide layer or diffusion of silicon away from the reaction front may be the s west processes* The effect of variation of time period on the thickness of the oxide layer formed has been investigated , The results show that 'the imam value is obtained after holding the silica particles for 20 nits, in molten alloy at all. temperatures* Tensile strength is estimated to be varying with the variation ik silica content,, maximum value is reached when silica volume /: is 2.5 to 3 • Fractured surfaces of corgpesite studied under SB . . have revealed that material failed either by propagat ton of particle cracks in the matrix or by decohensten of the oxide àiUca interface