METALLOGRAPHIC STUDY OF THE CASTING MADE FROM CMSX-6 SC NICKEL-BASED SUPERALLOY

Microstructural characterization is an important tool to optimize the properties of engineering materials. Quantitative metallography is a common technique, which provides three-dimensional estimations of phases and structure elements from two-dimensional images. Metallography has been described as both a science and an art [1]. Superalloys are high-performance alloys which exhibits excellent mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. Temperature and corrosion resistant materials such as nickel-based superalloys are prepared mostly with standard metallographic techniques. However, the results can be significantly improved by using finely graded CMP (chemical mechanical polish) polishing solutions on a high napped polishing pad. Sample preparation requires a certain degree of skills and experience, due to the high chemical resistance of most superalloys. Some chemical solutions are able to dissolve the. matrix and recover the gamma' residue, and some others solutions can be used to obtain a contrary effect-dissolve the gamma' phase precipitates and recover the. matrix residue. The aim of the presented research is to describe qualitatively and quantitatively the as-cast microstructure of CMSX-6 SC superalloy. The author's attention has been concentrated on the gamma' phase precipitates morphology. The results of using optical and scanning electron microscopy (SEM) are presented.