HIGH DEFORMATION CONSOLIDATION POWDER-METALLURGY PROCESSES FOR AN AL-LI ALLOY COMPOSITE

Citation
Hf. Lee et al., HIGH DEFORMATION CONSOLIDATION POWDER-METALLURGY PROCESSES FOR AN AL-LI ALLOY COMPOSITE, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 189(1-2), 1994, pp. 173-180
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science
ISSN journal
0921-5093
Volume
189
Issue
1-2
Year of publication
1994
Pages
173 - 180
Database
ISI
SICI code
0921-5093(1994)189:1-2<173:HDCPPF>2.0.ZU;2-9
Abstract
High deformation consolidation powder metallurgy (PM) processes for AI -Li alloy composites use a high degree of deformation and relatively h igh strain rates for consolidation, thus eliminating the problem of Li depletion. In this work, a PM process involving cold isostatic pressi ng at 350 MPa followed by hot extrusion at about 500 degrees C was use d to produce 8091 Al-Li composites reinforced with particulate SiC. Di fferent particle sizes of SiC were used. The composite materials posse ss increased modulus and hardness with increasing SiC content. Smaller reinforcement particles gave higher increases. However, the smallest particles used, 2.5 mu m, introduced agglomeration problems. Increasin g the SiC reinforcement content did not increase the yield stress and strain, but decreased the ultimate stress and fracture strain. This wa s attributed to the possibility that the SiC particles, by being fract ured in the consolidation process, acted as crack initiation points as well as stress concentration points. The results also indicate the li mitations of using such a particle reinforcement system.