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The research focuses on the high temperature oxidation resistance of martensitic heat-resistant steel. A new type of martensitic heat-resistant steel was developed with the addition of Al and Cu, and the oxidation behavior of the new martensitic heat-resistant steel at 650 °C and 700 °C was analyzed. The high temperature oxidation kinetics curves of new martensitic heat-resistant steel at 650 °C and 700 °C were determined and plotted by cyclic oxidation experiment and discontinuous weighing method. XRD technique was applied to qualitatively analyze the surface oxide of the material after oxidation. The surface and cross-section morphology of the material were observed by field emission scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), and the oxidation mechanism at high temperature was analyzed. The results show that the oxide film can be divided into two layers after oxidation at 650 ºC for 200 h. The outer oxide film is mainly composed of Fe and Cu oxides, and the inner oxide film is mainly composed of Al2O3, SiO2 and Cr2O3. After oxidation at 700 ºC for 200 h, the outer layer is mainly composed of Fe, Cu, Mn oxides, and the inner layer is mainly composed of Cr, Al and Si oxides. The addition of a small amount of Cu promotes the diffusion of Al and Si elements, facilitates the formation of Al2O3 and SiO2, and improves the high-temperature oxidation resistance of martensitic heat-resistant steel.

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In this paper, the addition of magnesium and copper was changed to investigate the effect of magnesium and copper on the tensile properties of ZA27(Zn-27Al) alloy. The experimental results showed that Zn-27Al-0.8Mg has the largest tensile strength of 294.61 MPa. The fracture of Zn-27Al-xMg alloy was mainly related to the newly precipitated magnesium phases (β+β´). For the Zn-27Al-xCu alloy, when the amount of copper added was 0.4wt.%, the tensile strength reached 292.58 MPa, and when the amount of copper added was 2.0wt.%, the elongation even reached 80%, indicating that the alloy has good plasticity. The fracture of the Zn-27Al-xCu alloy was mainly related to defects in the structure and the second phase particles.

Research and design of different components of molybdenum-cobalt alloy, including Mo-3Co alloy, Mo-6Co alloy, Mo-9Co alloy and pure molybdenum alloy. The weight loss of pure molybdenum alloy, Mo-3Co alloy, Mo-6 Co alloy and Mo-9Co alloy at 400 °C, 600 °C, 800 °C, 1000 °C after 1-hour oxidation was systematically analyzed. Observing the surface of the oxide layer, it was found that the Mo-6Co alloy was vigorously oxidized at 800 °C and 1000 °C to form volatile MoO3. As the cobalt content increased, the weight loss rate of the samples showed a downward trend at different oxidation temperatures. Granular oxides were formed when the Mo-6Co alloy sample was oxidized at 400 °C; when oxidized at 600 °C, scaly oxides were formed; when oxidized at 800 °C and 1000 °C, blocky or flaky oxides were formed. Addition of the element of cobalt can obviously alleviate the oxidation of molybdenum-based alloy specimens at high temperature.

In this research article, the molybdenum alloy was prepared by solid-solid doping, selecting pure Mo powder, amorphous Si powder, and B powder as the experimental raw materials for SLM molding. The density and mechanical properties of Mo-Si-B alloys prepared by SLM technology under different processes and compositions were explored, and at the same time, the microstructure of the obtained alloy was observed. The result shows that, with a laser power of 250 W, a scanning speed of 500 mm/s, and a scanning distance of 60 μm, the Mo4.5-Si2-B (at.%) alloy has the highest forming rate under the 120°parameters of the rotating scanning strategy, and the highest density is 94.22%.

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