The metal thickness uniformity of the micro-electroforming process determines the structural accuracy, surface finish, and functional characteristics, which directly affect the quality, performance, and reliability of the final parts. However, due to the non-uniformity of the electric field distribution, the problem of thickness non-uniformity in the micro-electroforming process has always been one of the key challenges limiting its application and development. The auxiliary cathode structure can improve the uniformity of electroforming thickness by regulating the cathode electrodeposition rate and electric field distribution and is widely used in the micro-electroforming process. In this study, with the micro-array metal die core as the research object, based on finite element simulations, the effect of the geometrical parameters of the auxiliary cathode on the thickness uniformity of electroforming is analyzed in depth. This study introduces the optimization method of the BP neural network and the NSWOA (Non-dominated Sorting Whale Optimization Algorithm) and achieves a significant improvement in the unevenness of electroforming thickness by designing and adjusting the parameters of the position, width, and shape of the auxiliary cathode. The unevenness of the microarray metal mold core is reduced to 4% from 475% without the auxiliary cathode, using the auxiliary cathode structure designed with this method.

The thickness uniformity of electroformed layers critically determines the dimensional accuracy, surface quality, and reliability of micro-electroformed devices. This work investigates nickel deposition under double-pulse current with a focus on quantifying the effects of positive-pulse current I avg , a , negative-pulse current I avg , c , and duty-cycle fractions D _a : D _c on thickness inhomogeneity and morphology, training and validating an artificial neural network (ANN) surrogate for rapid prediction, and ultimately identifying an optimal pulse window under practical bounds. With a fixed negative pulse, increasing the positive-pulse current (0.032 to 0.035 A) steadily reduces macroscopic thickness uniformity; the best uniformity occurs at 0.032 A, while the microstructure evolves from compact equiaxed grains to oriented/needle-like and eventually coarse faceted textures. Duty-cycle modulation strongly improves uniformity: raising D _a : D _c from 0.50:0.15 to 0.575:0.075 reduces thickness inhomogeneity from 352% to 125%. A crested porcupine optimizer (CPO)-initialized back-propagation artificial neural network (BP-ANN) surrogate trained on 1610 COMSOL ^® -generated samples (70/30 split) maps power-supply parameters to thickness inhomogeneity α and serves as a rapid proxy for simulations. Coupled with the Whale Optimization Algorithm (WOA) for single-objective minimization of α , the framework identifies optimal pulse parameters ( a ₁ – a ₄ ) = (0.0412 A, 0.066 A, 0.549, 0.081), yielding α ≈ 96.5% in simulation and verified experimentally by bright, fine-grained deposits with improved uniformity. A physics-guided hybrid framework is proposed—integrating COMSOL ^® secondary-distribution data into a CPO-initialized BP-ANN surrogate, followed by optimization using the WOA—which delivers experimentally validated improvements in thickness uniformity without auxiliary cathodes or shields, relying on pulse shaping alone.

Thickness gradients, residual stress and texture-related changes jointly constrain the dimensional reliability of nickel microelectroforming. This study examined how low-intensity magnetic-field magnitude and direction affect thickness uniformity, surface appearance, X-ray diffraction response and residual stress during nickel microelectroforming. Magnetic flux density, field angle, stirring rate and cycle-averaged current were varied, while an exploratory reduced-domain transport model was used to estimate the direct Lorentz-force-related contribution to near-cathode mass transfer, and a separate six-variable screening step supplied a fabrication trial. The response was non-monotonic: the mean residual-stress magnitude was 217.7 ± 16.6 MPa at 0 mT, increased to 317.0 ± 13.6 MPa at 5 mT, and decreased to 191.6 ± 18.9 MPa at 10 mT. Field rotation redistributed rather than eliminated thickness gradients, with the poorest combined surface, diffraction and stress response occurring at 60°. The tested 400 and 500 rpm conditions revealed a trade-off between residual stress and thickness uniformity at 10 mT and 90°. Integrating magnetic control with pulse-reverse current and auxiliary-cathode control produced a nickel micropillar mold with a nine-region mean-height range of 1.40 μm and a nonuniformity of 14.7%. The integrated route gave a mean pull-off stress of 2.07 ± 0.11 MPa (n = 3); cohesive failure within the adhesive indicates that this value represents a lower bound on the Ni/Cu interfacial load-bearing capacity.

Ni-W alloys are promising heterogeneous seed materials for directional solidification of Ni-based single-crystal superalloys. In this study, Ni-20 wt.% W (Ni-20W) seeds were used to initiate DD419 castings. Their solidification characteristics, melt-back behavior, interfacial microstructure, and orientation transfer were compared with those of DD419 homogeneous seeds. In two thermal cycles, Ni-20W had liquidus temperatures of 1492.6 and 1493.6 °C, with a critical nucleation undercooling of 14.5 °C in both cycles. DD419 had liquidus temperatures of 1388.8 and 1394.1 °C and undercoolings of 44 and 37 °C, respectively. Metallography and paired Laue measurements of one plate casting were consistent with orientation inheritance from Ni-20W to DD419. The software-reported differences in Theta and Alpha were 0.2° and 2.7°, respectively; the software-reported R value was 3.52. In the same-batch turbine-blade comparison, visible interfacial stray grains were observed on the examined starter-region surfaces of all six Ni-20W-seeded blades. No comparable features were observed on the examined surfaces of the three DD419 homogeneous-seeded blades. The maximum observed melt-back lengths were approximately 12 mm for Ni-20W and 45 mm for DD419. These observations indicate that orientation inheritance in the plate specimen did not ensure a defect-free starter region in the blade comparison. The two seed materials also showed markedly different melt-back behavior under the same nominal casting schedule.