EFFECTS OF SILICON ADDITIONS ON OXIDATION AND MECHANICAL BEHAVIOR OF THE NICKEL-BASE SUPERALLOY B-1900

摘要

Cast B-1900 test specimens with nominal additions of 0-, 0. 5-, and l-wt% Si were tested in oxidation, thermal fatigue, sulfidation, tension, and stress rupture and were also extensively studied metallographically. Alloy B-1900 modified with 0.6- or 1. 2-wt% Si exhibited oxidation resistance equivalent to that of aluminide-coated B-1900 during cyclic, high-gas-velocity oxidation tests. Resistances to thermal fatigue and sulfidation were improved by the Si additions, but aluminide-coated B-1900 is definitely superior in both respects. Stress-rupture tests at 1000° C of specimens given the standard heat treatment to simulate an aluminide coating cycle showed Si to be detrimental. However, application of another heat treatment increased the rupture life of the alloy with 0.6-wt% Si to that of the unmodified B-1900 given the standard heat treatment.