抄録
Amorphous alloys of a new type have been found in alloy systems of chromium-transition metals-carbon, such as Cr–Fe–C, Cr–Co–C, Cr–Ni–C, Cr–Nb–C, Cr–Mo–C and Cr–Ta–C, by a rapid quenching technique. Specimens were produced in the form of a continuous ribbon of about 1 mm width and 0.03 mm thickness by using a modified single roller quenching apparatus designed by the present authors. The carbon content in these amorphous alloys is limited to the range between about 15 and 23 at% and the alloy compositions are in the ranges of 9∼59 at% Fe, 15∼57 at% Co, 27∼51 at% Ni, 11∼17 at% Nb, 7∼23 at% Mo and 7∼13 at% Ta, respectively. These new alloys are expected as a high-hardness material with high thermal stability of structure. Vickers hardness number decreases by the addition of Fe, Co and Ni, while the value increases with an increase in Nb, Mo and Ta contents. Also, the amorphous structure of these alloys is thermally more stable as compared with the other amorphous alloys of metal-metalloid system reported so far. The maximum hardness and crystallization temperature are about 1400 DPN and about 1030 K, respectively. The effectiveness of alloying elements on increasing hardness and crystallization temperature decreases in the order of Nb, Ta, Mo, Fe, Co and Ni.
