PARTICLE INCORPORATION BY MELT STIRRING FOR THE PRODUCTION OF METAL-MATRIX COMPOSITES

Citation
Gs. Hanumanth et Ga. Irons, PARTICLE INCORPORATION BY MELT STIRRING FOR THE PRODUCTION OF METAL-MATRIX COMPOSITES, Journal of Materials Science, 28(9), 1993, pp. 2459-2465
Citations number
12
Categorie Soggetti
Material Science
ISSN journal
00222461
Volume
28
Issue
9
Year of publication
1993
Pages
2459 - 2465
Database
ISI
SICI code
0022-2461(1993)28:9<2459:PIBMSF>2.0.ZU;2-7
Abstract
The production of ceramic particle-reinforced metal-matrix composites by the melt-stirring technique involves two different steps: firstly, the establishment of particle-melt contact, and secondly, the wetting of the particles by the melt. The wetting behaviour of metal-ceramic s ystems has been studied extensively, whereas the contacting problem ha s been largely neglected. In this paper, a novel in situ thermal metho d has been used to investigate the kinetics of particle-melt contactin g, based on melt cooling during and immediately after the particle add ition. An enthalpy balance relates the amount of cooling and the fract ion of the particles contacting the melt. For the aluminium alloy (A35 6) with 15 vol % silicon carbide (17 mum diameter), it was found that only 16 % of the particles contacted the melt after mixing times of 15 min, but contact could be improved to 36 % by adding magnesium to the melt. The fraction contacting the melt agreed well with the particle volume fraction calculated independently. Sampling of the froth layer on top of the melt revealed that a large portion of the particles resi des there prior to incorporation into the melt.