Hideyo Kodama

Nickel Base Superalloys Single Crystal Growth Technology for Large Size Buckets in Heavy Duty Gas Turbines

A larger size bucket with superior high temperature strength is required for future land based gas turbines. From the viewpoint of high temperature mechanical properties, single crystal alloys are rather promising. To grow larger sized single crystals of nickel base superalloys, a two stage heating and bypass process in which single crystal growth paths are incorporated into large cross sectional positions such as platforms has been developed. It results in successful single crystal growth of alloys for buckets with a total length of 170mm and large lateral cross section. Characteristics of single crystal buckets made by the bypass process and properties of an alumina mold prepared for a single crystal casting are described herein.Copyright

Microstructure of Rapidly Solidified Nb3Al-X Ribbons

Nb-Al and Nb-Al-X(X is Cr,Ti or Zr) ternary alloys ribbons, with compositions around the A15 (Nb 3 Al) structure, a candidate intermetallic as an advanced high temperature material, were rapidly solidified by an arc melt spin process. The rapid solidification structure of these tri-niobium aluminide alloys and the relationship between formed phases and compositions of ribbons are investigated.