Ni‐P bilayers were prepared on AZ61 magnesium alloy by electroless plating method in dual baths with pH value of 11.0 and 5.5. The thickness, surface morphology, composition, structure and corrosion resistance of Ni‐P bilayer were observed and determined by scanning electron microscope (SEM), energy dispersive X‐ray spectrometry (EDX), X‐ray diffractometer (XRD) and electrochemical workstation. The results show that Ni‐P bilayer is composed of inner layer in mixed amorphous and nanocrystalline structure with phosphorus content of 3.9–4.0% and outer layer in amorphous structure with phosphorus content of 8.8–10.9%. The plating time of inner layer has a great impact on the morphology and corrosion resistance of Ni‐P monolayer and bilayer, and the corrosion resistance of Ni‐P bilayer is obviously higher than that of inner layer. The optimum plating condition for Ni‐P bilayer is the combination of inner layer's plating time of 30 min and outer layer's plating time of 180 min, under which Ni‐P bilayer gets a dense structure, smooth surface and higher corrosion resistance than that of single inner layer and outer layer.

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01570 aluminum alloy was cold rolled and annealed at different temperatures, and their microstructure, mechanical properties, pitting and stress corrosion cracking (SCC) behaviors were observed and determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion test, slow strain rate tensile (SSRT), and constant loading tests. The results reveal that the dislocations within the grains of alloy 01570 are transformed from dislocation tangles to dislocation walls and subgrains as the treatment varies from the cold rolled temper to the annealed tempers; at the same time, the tensile strength and SCC resistance of alloy 01570 are increased and the elongation is decreased, whereas the corrosion rate is negligibly influenced by the annealing treatments. Therefore, the annealed at 300 8C temper can be selected as the optimum heat treatment for the practical application of alloy 01570.