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The oxidation behavior of Ni-based superalloy GH586 which is treated by pack-cementation aluminizing was investigated. Scanning electron microscope and X-ray diffraction were used to analyze the microstructure of aluminide coatings and the surface morphologies of the oxide scales. Results show that the main phase of the aluminide coatings was NiAl. The aluminide coating can be formed at lower temperature due to the addition of rare earth oxide in the mixture powders. The thickness of aluminide coating at 900°C was about 110μm, and another aluminide coating with rare earth oxide Y2O3 at 800°C was about 38μm. The oxidation kinetics of aluminized specimens approximately followed a parabolic oxidation law at 1000°C. The morphology of the oxidation scales was primarily θ-Al2O3 with minor α-Al2O3. The scales of the coatings with rare earth oxide Y2O3 after oxidation was more dense.

It is a challenge to apply micromachining to the metal surface by conventional YAG laser. In this article, several experiments have been carried out to use micromachining on the surface of metallic specimen by frequency doubled Nd: YAG laser pumped by semiconductor. The mechanism of laser micromachining and the selective laser power, pulse duration, repetition frequency, scanning velocity and supplementing gas have been extensively studied and analyzed. The experimental results indicate that if the main technological parameters have been generally considered and optimized, positive quality of surface machining can be obtained.

This paper explores the properties of Fe40NiCrSiAl alloy treated by different methods. The hardness, elastic modulus and resistivity are tested. The results indicate that: after LSP to rolled Fe40NiCrSiAl alloy, the hardness increased 25.22%, the elastic modulus increased 7.17% and the resistivity decreased 39%. TEM photographs demonstrated that there appeared dislocations, martensite transformation and twin crystals inside the material after being treated by LSP. Twin crystals are the main reason attributing to the improvement of material electrical properties.