Volume 5, Issue 3 (May 1977)
Phase Analysis of Standard and Molybdenum-Modified Mar-M509 Superalloys
Phase characterization studies have been conducted by an ASTM Task Group on interlaboratory specimens of three Mar-M509-type superalloys heat treated to simulate service conditions. The results of the studies, employing X-ray and electron diffraction analysis and energy dispersive X-ray analysis, showed that the alloys contain (a) script-type metal-carbon (MC) carbides, (b) two types of eutectics (both containing M23C6-type carbides), (c) M23C6 carbides precipitated in the vicinity of script-type MC carbides and M23C6 eutectics, and (d) very fine MC carbides precipitated along crystallographic planes of the matrix phase. The molybdenum-modified Alloys XC-224 and XC-224Fe also contain M6C carbides. The compositional and crystallographic data for the phases are presented and discussed.