Cu based composite materials reinforced with Al-Cr preform produced by reactive melt infiltration
Krzysztof Naplocha
Quarterly No. 2, 2015 pages 78-82
DOI:
keywords: reactive infiltration, preform, combustion synthesis, oxidation resistance
abstract Composite materials were produced by reactive infiltration of a porous intermetallic Al9Cr4 preform whose structure was developed during combustion synthesis. Compacts of Al and Cr powders with a stoichiometric ratio of Al/Cr equal to 9/4 were placed and ignited in a microwave reactor. Due to the low enthalpy of the reaction, the samples were preheated. The reaction starts with partial melting of the Al particles producing a homogeneous structure with open porosity. The synthesis proceeded by intermediate phase transformations reaching a maximum temperature of ca. 1000°C. Next, the preforms were pressure infiltrated with molten Cu with interfacial diffusion of the composite elements. The intermetallic compound decomposed releasing Al which saturated the matrix and formed a Cu9Al4(Cr) phase. Simultaneously, the preform transformed into a mixture of globular precipitates of Cr52Al35Cu13 embedded in the Cu47Al41Cr12 phase. The produced composite materials exhibit significant heat and oxidation resistance. The developed protective layer was composed of Al2O3 oxides doped with Cr and Cu and growth with parabolic oxidation kinetics.