Microstructure, Creep and Fracture Toughness of Directionally Solidified NiAl/(Cr,Mo) Alloys Modified with Hf,SirTa,Ti Additions

摘要

A statistical design of experiments (DOE) strategy was implemented to optimize alloys based on the Ni-33Al-31Cr-3Mo eutectic system using small amounts of potential strengthening elements (Hf, Si, Ta, Ti). Following the analysis of the DOE results, several alloys were selected for direction-ally solidification (DS) utilizing a modified Bridgeman technique. The as-grown alloys were microstructurally examined by optical and scanning electron microscopy. They were also evaluated for fracture toughness at room temperature and compressive properties at 1300K. The microstructures and mechanical properties of these DS DOE alloys are discussed and compared to the directionally solidified Ni-33Al-31Cr-3Mo base composition.