Solid State Phenomena Vol. 366

Abstract: To pinpoint the relationship between the microstructure and corrosion resistance of the B10 copper tube, the copper tubes were annealed at 780°C and 810°C, respectively. Then the simulated seawater full immersion experiment was conducted. The corrosion film, grain size, boundary characteristics, and intragranular microstructure of the alloy were analyzed by OM, SEM, EBSD, and TEM. The results implied that the corrosion rate of the 810°C annealed copper tube is about 0.028 mm/a, which is 1.9 times that of the 780°C annealed copper tube. The average grain size of 810°C annealed copper tube is about 38.85 μm and the low ΣCSL account for 64.8 %, which is 1.5 times and 1.4 times that of 780°C annealed copper tube, respectively. There is a complete spinodal decomposition structure within the grain in an 810°C annealed copper tube, but there is an incomplete spinodal decomposition structure in a 780°C annealed copper tube. Theoretical analysis indicated that the large-sized grain clusters could be formed by numerous low-layer fault energy twin boundaries Σ3, and low ΣCSL combination Σ3, Σ9, Σ27, which can block the large crystal boundaries network, inhibit the phase precipitation and prevent invading of corrosive elements along the large crystal boundaries. The intragranular spinodal decomposition structure can improve the strength and toughness of the B10 copper tube, reduce the initiation of surface microcracks during service, and thus reduce pitting and crevice corrosion.

Abstract: The effect of trisodium citrate on the electrodeposition of nickel-copper-molybdenum in sulfate solution was explored in this paper. According to the results of the nickel-copper-molybdenum electrodeposition experiment, adding a certain amount of trisodium citrate into the electrodeposition solution inhibited the hydrogen precipitation reaction and accelerated the crystallization process on the plated surface to a certain extent, thereby improving the cathodic current efficiency. However, no change occurred to the nucleation mode in the process of electrodeposition crystallization, and it was consistent with the theoretical value of instantaneous nucleation before the peak current (t/t_m≤ 1) was reached. The theoretical values of instantaneous nucleation were consistent. The epitaxial growth rate constant K^* of the crystals was reduced after the addition of trisodium citrate into the electrodeposition solution, indicating the inhibitory effect of trisodium citrate on the growth of crystals in the electrodeposition solution. The diffusion coefficient of the nickel-copper-molybdenum ligand ions was reduced as well, suggesting the inhibitory effect of adding trisodium citrate into the plating solution on the cathodic mass-transfer process, which is conducive to promoting its cathodic polarization. Meanwhile, the growth rate of crystals was significantly affected by the applied potential.

Abstract: In this paper, invoking the mechanism of laser phase change hardening, the presence of latent heat of phase change, the temperature-dependent fluctuation of the thermal coefficient, and the disparity of microstructure austenitizing during rapid heating and static heating are duly reckoned. The repercussion of laser energy density distribution on the geometric configuration of the laser quenching phase change zone is probed via a numerical simulation model. Concurrently, the self-developed laser shaper is employed to modify the energy allocation of the conventional laser, and laser quenching is executed on the surface of AISI1045 steel with the spotlight subsequent to the shaper. Through the comparison of the cross-sectional area of the experimental sample phase change zone and the simulated phase change zone, the projected error ratio of the model established in this research is less than 10%.

Abstract: Titanium alloy fasteners are extensively used in advanced fields such as aerospace due to their corrosion resistance, high-temperature endurance, low density, and high strength-to-weight ratio. In practical applications, fatigue failure is the primary failure mode for these fasteners. Besides the operational environment, the manufacturing process, especially surface treatment techniques, plays a crucial role in affecting the fatigue life of titanium alloy fasteners. This paper examines the impact of three surface treatment processes-rolled fillet, pulsed anodization, and molybdenum disulfide coating－on the fatigue life of titanium alloy fasteners through orthogonal experiments. The study finds that both rolled fillet and molybdenum disulfide coating significantly influence the fatigue life. This effect is associated with residual stresses, where compressive residual stress initially increases with rolling pressure but subsequently decreases, and reduces as the thickness of the molybdenum disulfide lubricating film rises.