Infiltration of Al{sub 2}O{sub 3} short-fiber preforms during squeeze
- Univ. of Oxford (United Kingdom)
- Lucas Advanced Engineering Centre, Solihull (United Kingdom)
This paper describes a series of experiments designed to investigate the process of infiltrating a commercial A357 Al-7wt%Si-0.6wt%Mg alloy into Saffil 20vol% 3--3.5 {micro}m mean diameter, 500 {micro}m mean length discontinuous Al{sub 2}O{sub 3} fiber preforms during squeeze casting with applied pressures of 0--100 MPa, melt temperatures of 700--900 C and die and preform temperatures of 300 C. The main conclusions are: (1) in melt infiltration and squeeze casting, presolidification of the liquid alloy takes place during the time delay between die filling and pressurization; (2) presolidification forms a shell of coarse columnar grains of {alpha}-Al dendrites; (3) the remaining solute enriched liquid infiltrates the preform leading to macrosegregation within the composite; (4) needle-like primary FeSiAl{sub 5} and blocky primary (FeMn){sub 3}Si{sub 2}Al{sub 15} intermetallics, formed by enrichment of the solute during the time delay, are filtered during infiltration at the composite/monolithic interface; (5) stresses build up within the preform, leading to cracks and fragmentation particularly at the locating supports; (6) shrinkage pores, cracks and uninfiltrated regions in the composite are all force fed with eutectic liquid as the pressure builds up at the end of the ram travel; (7) high applied pressure leads to a fine grained structure within the preform, due to increased heat flow rates between the die and the solidifying metal.
- OSTI ID:
- 186743
- Report Number(s):
- CONF-950201-; ISBN 0-87339-316-3; TRN: IM9609%%15
- Resource Relation:
- Conference: Annual meeting and exhibition of the Minerals, Metals and Materials Society (TMS), Las Vegas, NV (United States), 12-16 Feb 1995; Other Information: PBD: 1995; Related Information: Is Part Of Synthesis/processing of lightweight metallic materials. Proceedings; Froes, F.H.; Suryanarayana, C. [eds.] [Univ. of Idaho, Moscow, ID (United States). Inst. for Materials and Advanced Processes]; Ward-Close, C.M. [ed.] [Defence Research Agency, Farnborough (United Kingdom)]; PB: 380 p.
- Country of Publication:
- United States
- Language:
- English
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