Abstract
Multi-phase hard materials free from binder metals are used to meet the requirements of high wear resistance and high temperature stability. Investigations of properties and wear behavior showed extremely high values in carbide/boride combinations, particularly a TiC/TiB2 mixture of a 1∶1 molar ratio. The pseudobinary phase diagram shows low intersolubilities. High-resolution Auger Electron Spectroscopy was used to examine mixed two-phase TiC/ TiB2 hard materials and compare them to pure TiC and TiB2. The AES analyses were carried out on cross sections and fresh fracture surfaces. At the grain boundaries in pure TiC as well as in pure TiB2, some amounts of Fe, Cr, Co and P can be detected. These elements are already in the powders as received. In addition, an O-rich phase has been identified in hot pressed TiB2. The same impurity elements as in the pure materials can be found at a few phase boundaries and triple points in two-phase TiC/TiB2 with a thickness of a few monolayers. However, large areas of the fracture surface were found to carry a TiBxCy phase on the grains. The considerable increase in wear resistance and fracture toughness of TiC/TiB2 compared to pure TiC and pure TiB2 can be explained by the presence of this TiBxCy phase.
Published Version
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