Squeeze casting and melt infiltration of locally reinforced Al-4.5wt%Cu/20vol%Al2O3 discontinuous fibre MMC ingots

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Author(s)

  • H G Kang
  • H I Lee
  • P R G Anderson
  • B Cantor

Department/unit(s)

Publication details

Title of host publicationPROCESSING AND FABRICATION OF ADVANCED MATERIALS IV
DatePublished - 1996
Pages509-527
Number of pages19
PublisherMINERALS, METALS & MATERIALS SOC
Place of PublicationWARRENDALE
EditorsTS Srivatsan, JJ Moore
Original languageEnglish
ISBN (Print)0-87339-337-6

Abstract

This paper describes a series of experiments designed to investigate the process of infiltrating a model binary alloy with a composition of Al-4.5wt%Cu into Saffil 20vol% 3-3.5 mu m mean diameter, 150+/-50 mu m long discontinuous Al2O3 fibre preforms during squeeze casting with an applied pressure of 100MPa, melt pouring temperatures of 750-850 degrees C and die and preform temperatures of 300 degrees C. The main conclusions are: (1) in melt infiltration and squeeze casting, presolidification of the Al-4.5wt%Cu alloy during the time delay between die filling and pressurisation causes solute enrichment in the remaining liquid alloy; (2) too much presolidification during the time delay between die filling and pressurisation leads to a high volume fraction of coarse alpha-Al dendrites, which remain filtered outside the preform at the point where infiltration begins; (3) heat extraction by the cold fibres further enriches the solute content of the remaining liquid alloy and leads to a fine grain size within the composite region of the casting; (4) stresses build up within the preform, leading to preform distortion and are shaped cracks from stress concentrations at the locating supports; and (5) shrinkage pores and preform cracks are force fed with solute enriched eutectic liquid as the pressure builds up at the end of infiltration and squeeze casting, leading to macrosegregated bands in the monolithic and composite regions of the casting.

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