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The microstructure and corrosion of rare earth NiCrMoY alloy made by atomisation and oxygen–acetylene flame spray and high-frequency induction remelting technique were investigated by means of scanning electron microscopy, energy spectrum, X-ray diffraction, uniform corrosion of laboratory immersion tests and anodic polarisation curve of three-electrode potentiodynamic scans. The results showed that compared to the coatings of Ni60A, the microstructure of NiCrMoY alloy coatings was finer, some bulk- and needle-like hard microstructures were precipitated, and a new phase MoB was produced. The corrosion rate of NiCrMoY alloy coatings is better than that of Ni60A coatings in HCl, H2SO4, HNO3 and artificial seawater.

The microstructures were observed in C–Mn steel and statistical analysis of the inclusions produced when trace amounts of rare earth were added to the steel. The results show that the content of intragranular acicular ferrite decreased in the order of being treated with La+Ce/La/Ce in C–Mn steel after the treatment of different kinds of rare earths. The optimum mass ratio of La and Ce for La+Ce combined treatment is 3:1.The best incubation time after Le+Ce (3:1) treatment is 5 min. The size of inclusion nuclei favouring intragranular acicular ferrite nucleation concentrates in the range of 1–4 μm. The disregistries between rare earth inclusions and α-Fe are small, which plays an important role in rare earth inclusions inducing intragranular acicular ferrite nucleation.