Preparation of molybdenum‐base alloy single crystals Available to Purchase

A study of the preparation of molybdenum‐base alloy single crystals was conducted using an electron beam zone melting method. Due to the outgassing, multiple zone passes were always necessary. For alloys of molybdenum (Mo) with up to 11 atomic percent of niobium (Nb), a high scan rate 54.9 mm/hour was found to be able to produce satisfactory single crystals. No difficulty was encountered when growing Mo‐Nb alloys which possessed complete solid solution characteristics because of their small temperature difference between the solidus and the liquidus lines. However, for Mo‐Hf alloys, the critical scan rate for single crystal formation was found to depend on Hf content in an inverse manner. Slower scan rates were needed for alloys with higher Hf contents. As a result, for Mo‐3.75%Hf and Mo‐5%Hf alloys, the scan rates were to about 11 mm/hour and 1.8 mm/hour respectively. In order to avoid the significant solute segregation during the salification along the scanning direction, the scanning rate based on experimental findings for Mo‐Hf alloys must be above 22.4 mm/hour. Therefore, under this consideration, the maximum Hf content in Mo‐Hf alloys was limited to about 2.8%.