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THE INFLUENCE OF SEVERE PLASTIC DEFORMATION ON STRUCTURE AND PROPERTIES OF ALUMINUM MATRIX COMPOSITES

  • : Gennadii Bagliuk1, Yulia Shishkina1
  • : 1Institute for problems of materials science
  • : PDF Download
  • : 2014

Abstract

The aim of the article was the investigation for effect of severe plastic deformation on structure and properties of aluminum matrix composites produced with use of hot (at 600 0C) twist extrusion (TE) from mixtures of Al and Al-TiC master alloy powders. Three passes of TE was used to make the composite specimens. The microstructure morphology and properties of the samples after each TE passage was studied. Composite structure after TE consists of two phases: aluminum matrix and agglomerates of hardening phase, which the size was 10÷150 microns. The agglomerates of the hardening agent consists primarily of titanium carbide particles with a size of 1-1.5 microns of nearly spherical shape. The deformation of hardening phase agglomerates and their drawing along the material flow direction takes place after TE resulting distinctly expressed texture in material structure. The degree of material texture significantly increased from first to the third TE passage. Severe plastic deformation of hard phase is accompanied by its refinement, but after first two TE passes along with grinded agglomerates fairly large agglomerates of 100÷120 microns size are present too. Only the third TE passage of the samples results in predominant presence in the composite structure of agglomerates wich average size does not exceed 25÷30 microns. Thus, the degree of size uniformity of the agglomerates reinforcing phase increases with the percentage of master alloy content and with increasing of passes number. As a result of structural changes owing to preforms deformation the composite properties changed too. With an increasing of TE passes number and the content of the hardening phase the density and hardness of the samples increases.
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