Abstract
The effects of B content and the heat treatment on the properties of gas atomized powders with Ni - 22 mass% Cr - X mass% Mo - Y mass% B compositions ((X, Y) = (23, 1.0), (26, 1.6), (30, 2.1), (33, 2.6)) were investigated. The powders were produced by gas atomization, followed by sieving under 150 µm in the particle size. Then the powders were heat treated at various temperatures to investigate the effects of the temperatures.
As a result, the powders with less than 1.6 % B before the heat treatment consisted of only Ni - based supersaturated solid solution with B. On the other hand, in the powders with more than 2.1 % B before the heat treatment, not only Ni - based matrix but also coarse complex boride were observed. Tetragonal M3B2 type complex boride precipitated in all powders after the heat treatment at more than 1073 K. Furthermore, all examined powders after the heat treatment at 1473 K had almost the same matrix composition as Ni - 22 mass% Cr - 16 mass% Mo. Vickers hardness of these powders increased with increasing B content.
