NI-BASE ALLOY CONTAINING INTERMETALLIC COMPOUND NI3SI AND ITS MANUFACTURE

摘要

PURPOSE:To improve the corrosion resistance to high concn. sulfuric acid and ductility in an Ni-base alloy by incorporating a specified amt. or above of Si into an Ni-Si alloy, stabilizing an Ni3Si phase (beta phase) therein and refining its grain size into specified value or below. CONSTITUTION:This alloy contains, by weight, 10 to 14% Si and the balance Ni and has =10mu grain size. Furthermore, one or more kinds of 0.5 to 4.5% Cu and 0.3 to 2.5% Ti or 0.5 to 6% Nb may be incorporated therein. This alloy shows excellent corrosion resistance even to sulfuric acid having high concn. of 60% as well as has ductility. As for the content of Si, at least 10% is required for showing its corrosion resistance; on the other hand, in the case of 14%, an Ni5Si2 phase is precipitated to deteriorate its ductility very brittlely. For manufacturing the above-mentioned alloy, hot extrusion is executed to the alloy having the above-mentioned compsn. under the condition of =1.5 extrusion ratio to refine its crystalline grains.