The dilution rate has a significant impact on the composition and microstructure of the coatings, and the dilution rate and process parameters have a complex coupling relationship. In this study, three process parameters, namely laser power, powder feeding rate, and scanning speed, were selected as variables to design the orthogonal experiment. The dilution rate and hardness data were obtained from AlCoCrFeNi coatings based on orthogonal experiments. Then, a BP neural network was used to establish a prediction model of the process parameters on the dilution rate. The established BP neural network exhibited good prediction of the dilution rate of AlCoCrFeNi coatings, and the average relative error between the predicted value and the experimental value was only 5.89%. Subsequently, the AlCoCrFeNi coating was fabricated with the optimal process parameters. The results show that the coating was well-formed without defects, such as cracks and pores. The microhardness of the AlCoCrFeNi coating prepared with the optimal process parameters was 521.6 HV_0.3. The elements were uniformly distributed in the microstructure, and the grain size was about 20–60 μm. The microstructure of the AlCoCrFeNi coating was only composed of the BCC phase without the existence of the FCC phase and intermetallic compounds.

Wire-arc additive manufacturing (WAAM) has been considered as one of the potential additive-manufacturing technologies to fabricate large components. However, its industrial application is still limited by the existence of stress and distortion. During the process of WAAM, the scanning pattern has an important influence on the temperature field, distortion and final quality of the part. Four kinds of deposition patterns, including sequence, symmetry, in–out and out–in, were designed to deposit H13 steel in this study. An in situ measurement system was set up to record the temperature history and the progress of accumulated distortion of the parts during deposition. An S value was proposed to evaluate the distortion of the substrate. It was shown that the distortion of the part deposited by sequence was significantly larger than those of other parts. The distortion deposited by the out–in pattern decreased by 68.6% compared with sequence. The inherent strain method and strain parameter were introduced to expose the mechanism of distortion reduction caused by pattern variation.

The Ni60A-Cr₃C₂ coatings with different Nb addition were prepared by laser cladding. The microstructure was observed by SEM and TEM. The chemical composition of phases was studied by X-ray diffractometer and Electron Probe Micro-analyzer (EPMA). Microhardness and wear behaviour were measured by microhardness tester and wear tester, respectively. The results show that the main phases in Ni60A-Cr₃C₂ coating are γ-Ni, Cr₇C₃, Cr₂₃C₆, Ni₃Si₂, Ni₃B and CrB. With Nb addition, the NbC phase appears in the coatings. The size and volume fraction of NbC increase with the increase of Nb addition. The hardness and wear resistance increase first and then decrease with the increase of Nb addition. The micro-hardness of coatings with 2 wt-% Nb addition is the highest, reaching 1046.6 Hv0.2. The relative abrasive resistance of coatings with 3 wt-% Nb addition is the best, and is 2.33 times that of Nb-free coatings.