By utilizing the excellent properties of a boride, a new type of sintered hard alloy has been developed. This alloy, categorized as a cermet, is produced by liquid phase sintering and comprises a M
2B (M: metal) boride as a hard phase and a ferrous binder phase containing Cr, Ni and other alloying elements.
In the present investigation, the sintering phenomena of Fe-(4-8) wt%B-(0-30) wt%Cr-0.3 wt%C alloys are studied by means of TG-DTA, dilatometric measurements and x-ray diffractometry. In addition, the mechanical properties of the sintered alloys are discussed.
The results can be summarized as follows:
(1) The hard alloy comprises an Fe
2B type boride as a hard phase and a ferrous binder phase containing Cr and C. When the hard alloy contains more than 10 wt% Cr, both Fe
2B and Cr
2B type borides coexist.
(2) The liquid phase sintering of the alloy is attained by two liquid forming reactions, namely, γ-Fe +Fe
3 (B, C)+M
23(B, C)6 L
1 and γ-Fe+Fe
2B L
2, the latter reaction occurring in a higher temperature range.
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