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Scanning and transmission electron microscopy study of the microstructural changes occurring in aluminium matrix composites reinforced with SiC particles during casting and welding: interface reactions
Author(s) -
A. Ureña,
Gómez de Salazar Jm,
L. Gil,
Escalera,
J. L. Baldonedo
Publication year - 1999
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.1999.00610.x
Subject(s) - materials science , transmission electron microscopy , composite material , aluminium , scanning electron microscope , welding , casting , matrix (chemical analysis) , microstructure , metallurgy , nanotechnology
Processing of aluminium matrix composites (AMCs), especially those constituted by a reactive system such as Al–SiC, presents great difficulties which limit their potential applications. The interface reactivity between SiC and molten Al generates an aluminium carbide which degrades the composite properties. Scanning and transmission electron microscopes equipped with energy‐dispersive X‐ray spectroscopes are essential tools for determining the structure and chemistry of the Al–SiC interfaces in AMCs and changes occurring during casting and arc welding. In the present work, an aluminium–copper alloy (AA2014) reinforced with three different percentages of SiC particles was subjected to controlled remelting tests, at temperatures in the range 750–900 °C for 10 and 30 min. Arc welding tests using a tungsten intert gas with power inputs in the range 850–2000 W were also carried out. The results of these studies showed that during remelting there is preferential SiC particle consumption with formation of Al 4 C 3 by interface reaction between the solid SiC particle and the molten aluminium matrix. The formation of Al 4 C 3 by the same mechanism has also been detected in molten pools of arc welded composites. However, in this case there was formation of an almost continuous layer of Al 4 C 3 , which protects the particle against further consumption, and formation of aciculate aluminium carbide on the top weld. Both are formed by fusion and dissolution of the SiC in molten aluminium followed by reaction and precipitation of the Al 4 C 3 during cooling.