Features of the phase composition of nickel alloys with high tungsten and molybdenum contents

Abstract

1. In the high-temperature hardened condition with a total tungsten and molybdenum content in the alloys of not more than 8 at. % α2, σ, and μ type excess phases are not formed and only complex carbides are present. In the alloys without molybdenum but containing 6.5 at. % W hardening α2-phase is precipitated. 2. The high-temperature strength of alloys containing ≥6.5 at. % W is higher than of alloys containing about 8 at. % W+Mo, which is related not only to hardening by these elements of the γ-solid solution but also to formation of excess α2-phase. 3. In the alloys containing more than 5–6% each of W and Mo (or ΣW+Mo≥5 at. %) type M6C binary chromium carbide is present, while with ΣW+Mo≤5 at. % type M23C6 cubic carbide is precipitated, which has a positive influence on the high-temperature strength of the investigated alloys.