Aluminium Alloying of the Binder Phase in WC-Ni-Co-Cr Cemented Carbides: AlN vs. TiAl_3 Additions. Effect of Solution Aging Treatments

摘要

The binder phase of WC based cemented carbides has been alloyed by adding two different aluminium compounds to mixtures comprising WC, Ni, Co and Cr_3C_2 powders. These compounds are titanium aluminide (TiAl_3) and aluminium nitride (AlN). The sintering behavior of these materials has been analyzed by dilatometric and calorimetric techniques showing that shrinkage and melting phenomena are strongly affected by the energy of the milling process. Milling also affects the amount of Al that is dissolved in the binder phase during sintering, since as the energy is reduced less Al is lost to the formation of alumina precipitates. SEM-EDS analyses confirm that TiAl_3 dissolves faster than AlN in the Co-Ni-Cr-W binder phase. Solution aging treatments appied to these materials induce the precipitation of γ'-like phases with significant effect on the overall hardness of the composite material. The effect of time and temperature are being investigated for different Al contents.