Epitaxial Growth of Ni-Based Superalloys Using Laser and Spark Deposition

Abstract

In this paper, epitaxial growth on Ni-based single crystals was achieved by using spark deposition and laser powder deposition. Different Ni-based substrates, such as CMSX-4, TMS 138A as well as deposition materials: NiCrAl, Rene N4 and modified 4.5th generation single crystal alloys were used. The deposited layers were analysed by laser confocal microscopy, FEG-SEM, X-ray and electron backscatter diffraction (EBSD), had very little dilution and epitaxial growth was confirmed for the deposits made using Rene N4 electrodes. The deposition time at 100 V voltage, 850 W power and 110 Hz frequency was 3min and the layer thickness varied from 0.3 to 0.5 mm. Cracks were observed in certain areas with the formation of stray grains. In order to investigate the influence of the laser processing during multiple build up, specimens with one and ten layers were manufactured. The total layer thickness on substrates was 0.3 mm and 2 mm, respectively. The processing parameters were: laser power of 500 W, laser beam diameter of 0.6 mm and the z displacement was equal to 80% of the layer height. The laser deposition also resulted in successful epitaxial growth and minimal defects (pores or cracks), however the clads presented high dilution.