Laser Cladding of Ni+Cr+Al+Rare Earth Alloys for Improved Oxidation and Hot Corrosion

摘要

Alloys and coatings for alloys for improved high temperature service life under aggressive atmosphere are of great contemporary interest. There is a general consensus that addition of reactive elements such as Hafnium will provide many beneficial effects for such alloys. The laser cladding technique was used to produce Nickel-Iron-Chromium-Aluminum-Hafnium alloys. The laser cladding technique was used to produce Ni-Fe-Cr-Al-Hf alloys with extended solid solution of Hf. A 10 kW carbon dioxide laser with mixed powder feed was used for laser cladding. Optical, scanning electron microscopy (SEM) and scanning transmission electron (STEM) microscopy were employed for microstructural evolution of alloys produced during laser cladding processes. The electron probe microanalysis and the auger electron spectroscopy were also used for microchemical analysis of different phases. Microstructural studies revealed a high degree of grain refinement, considerable increase in solubility of Hf in matrix and Hf rich precipitates and new metastable phases. This paper will report the microstructural development in this laser clad Ni-Fe-Cr-Al-Hf alloy.