Bonding of Cr_3C_2 base cermets onto steel substrates by powder metallurgical technique, so called sinter-bonding, is expected to be a smart process to produce a composite material possessing high strength. This process requires that a densification of the cermet and a bonding at the interface between the cermet and the substrate proceed simultaneously. Pseudo-ternary Cr_3C_2-Ni-WB cermets can be sintered to full density at temperatures lower than 1450K. The liquid phase formed by the eutectic reaction between added WB and Ni considerably reduces the sintering temperature of the Cr_3C_2-Ni cermet, providing the feasibility of the sinter-bonding with AISI 1045. In the case of the cermet without WB, a satisfactory sinter-bonded body could not be obtained, because an excessive reaction betwen Cr_3C_2 particles and AISI 1045 prior to the densification of the cermet generates a large amount of a liquid phase at the interface and caused remarkable grain coarsening of the carbides and reduction of bonding strength. The coarsened carbide particles near the interface formed by a direct reaction between Cr_3C_2 particles and AISI 1045 were identified as a M_7C_3 type chromium carbide containing W and Fe. WB addition to the Cr_3C_2-Ni cermet is essential to obtain the satisfactory bonding strength and microstructure between the cermet and the steel substrate.
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