The pitting corrosion behavior of 7150 aluminum alloy was studied by electrochemical impedance spectroscopy (EIS) in the sodium chloride and hydrochloric acid solution. Based on EIS features and corrosion morphologies as well as corrosion potential, the process of pitting corrosion could be clearly divided into four stages: at the first stage, the Nyquist diagram was composed of two overlapping capacitive loops at the high-medial frequency and one inductive loop at the low frequency. At the second stage (metastable pits developing stage), there existed one small capacitive loop at the high frequency and one big capacitive loop at the medial frequency. At the third stage (stable pits developing stage), two time constants were more clearly distinguished, corresponding to two obvious capacitive loops. At the fourth stage, there appeared one capacitive loop, attributing to uniform corrosion. An equivalent circuit was designed to fit EIS, and the experimental results and the fitted results had good correspondence.

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AlTiN, AlTiBN, and AlTiTaN coatings were deposited on cemented carbide substrate by cathodic arc evaporation. Scanning electron microscopy, X-ray diffraction, nanohardness testing, and scratch testing were used to examine the coating thickness, microstructure, hardness, adhesion strength, and oxidation resistance. The incorporation of B and Ta into the AlTiN coatings increased their hardness and oxidation resistance. In titanium-milling experiments using these three coatings, AlTiBN-coated carbide tools had the longest lifetime at cutting speed of 60 m/min. This is attributed to less delamination and chipping at the cutting edge, due to the coating's high hardness, good oxidation resistance, and sufficient adhesion strength. The major wear mechanisms of these coated tools are adhesive wear, oxidation, and chipping.

The effect of deformation on the stress–corrosion cracking (SCC) of Al–Zn–Mg–Cu alloys is studied by slow strain rate technique (SSRT) and bolt‐loaded double cantilever beam (DCB) tests. Results show that with the deformation increasing, the undissolved particles and subgrain size decrease whereas the fraction of recrystallization increases after solution treatment. The susceptibility to SCC by SSRT and DCB tests varies on different deformation amount alloy, in which cause is discussed.

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