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Quasicrystalline coatings through laser processing: a study on process optimisation and microstructure evolution

Chattopadhyay, K and Biswas, K and Bysakh, S and Phanikumar, G and Weisheit, A and Galun, R and Mordike, B (2001) Quasicrystalline coatings through laser processing: a study on process optimisation and microstructure evolution. In: Quasicrystals - Preparation, Properties and Applications. Symposium, 27-30 Nov. 2000, Boston, MA, USA, K15.3.1-K15.3.12.

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Abstract

Composite coatings containing quasicrystalline (QC) phases in Al-Cu-Fe alloys were prepared by laser cladding using a mixture of the elemental powders. Two substrates, namely pure aluminum and an Al-Si alloy were used. The clad layers were remelted at different scanning velocities to alter the growth conditions of different phases. The process parameters were optimized to produce quasicrystalline phases. The evolution of the microstructure in the coating layer was characterized by detailed microstructural investigation. The results indicate presence of quasicrystals in the aluminum substrate. However, only approximant phase could be observed in the substrate of Al Si alloys. It is shown that there is a significant transport of Si atoms from the substrate to the clad layer during the cladding and remelting process. The hardness profiles of coatings on aluminum substrate indicate a very high hardness. The coating on Al-Si alloy, on the other hand, is ductile and soft. The fracture toughness of the hard coating on aluminum was obtained by nanoindentation technique. The $K_{IC}$ value was found to be $1.33 MPa m^{1/2}$ which is typical of brittle materials

Item Type: Conference Paper
Additional Information: Copyright of this article belongs to Materials Research Society
Keywords: aluminium alloys;brittleness;claddings;composite materials;copper alloys;crystal microstructure;ductility;fracture toughness;hardness;indentation;iron alloys;laser beam;effects;melting;optimisation;powders;quasicrystals;stoichiometry
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 08 Aug 2007
Last Modified: 17 Aug 2011 09:20
URI: http://eprints.iisc.ernet.in/id/eprint/10452

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