FeNiCoCrNb_x (x: molar ratio, x = 0, 0.1, 0.2, 0.3) high entropy alloy coatings (HEACs) were fabricated on 316 stainless steel (SS) by laser cladding (LC). Experimental results showed that the addition of Nb increased the lattice constant of FeNiCoCrNb high entropy alloy system. HEAC exhibited the transformation from columnar crystal at the interface to equiaxed crystal at the surface on the cross-sectional plane because of the change in the temperature gradient (G) and solidification rate (R). When x = 0.3, lamellar Laves phases appeared in ID. The microhardness of the four HEACs was 1.78, 2.19, 2.30 and 2.37 times that of 316 SS. The HEAC with x = 0.3 as well as 316 SS exhibited typical p-type semiconductor characteristics, which showed excellent corrosion resistance as indicated by the lowest $I_{\mathrm{corr}}$ of 2.46 × 10⁻⁹ A cm⁻² and a larger passivation region with 2 times that of 316 SS.

Bending fatigue significantly affects the mechanical stability and lifespan of biomedical implants, such as bone plates and orthopaedic fixation devices, which undergo cyclic loading in the human body. This study examines the microstructure, porosity, and bending fatigue properties of PBF-LB/M SS316L. Samples were analysed across three faces (top, front, and side) using optical microscopy (OM) and scanning electron microscopy (SEM) to observe microstructural features and porosity. Elemental composition was measured by energy-dispersive X-ray spectroscopy (EDX). Phase structures and grain orientations were characterised via X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). Four-point bending fatigue tests, conducted under two loading conditions, below and slightly above the yield point, demonstrated that defects inherent to the PBF-LB/M process, particularly micropores and unmelted powder particles, strongly influence fatigue crack initiation. Real-time monitoring of crack initiation and propagation on the external sample surface was performed using a high-speed digital microscope. These findings indicate the influence of microstructural defects on fatigue performance in PBF-LB/M SS316L, supporting the design and development of more reliable patient-specific biomedical implants.

This study employs homogeneous material laser cladding to fabricate a metallurgically bonded repair layer compositionally identical to the TA15 substrate. The microstructure and phase composition were characterized using XRD, SEM, EBSD, and XPS, while electrochemical and wear tests were performed to evaluate performance. The results show that ultrafast solidification produces a fine acicular microstructure with refined grains and reduced BCC phase content. At the optimal energy density (S2, 31.3 J/mm ³ ), the repair layer exhibits a microhardness of 455 ± 6 HV, representing a 41% increase over the substrate, and achieves a wear rate as low as 2.61 × 10 ^{− 4} mm ³ /N·m. XPS analysis confirms that grain refinement promotes the formation of a dense TiO ₂ -based oxide film, which effectively suppresses Cl ⁻ ion penetration, leading to a low corrosion current density of 1.81 ± 0.06 × 10 ^{− 2} μA/cm ² . These findings demonstrate that compositionally matched laser cladding not only enhances wear and corrosion resistance but also provides a reliable strategy for additive remanufacturing of critical titanium alloy components.

A gradient alloy steel prepared by laser melting deposition (LMD) was subjected to two heat treatments (quenching-intercritical quenching denoted as Q-IQ and quenching-intercritical quenching-tempering denoted as Q-IQ-T). Results showed that martensite microstructure was changed to a duplex microstructure of martensite and ferrite after heat treatment, with a small number of Cr₂₃C₆ phases appearing. The samples before and after heat treatment exhibited random crystallographic orientation, while the grain was refined and the fraction of Cr₂₃C₆ increased after heat treatment. The samples after heat treatment possessed more slip systems and exhibited a decrease in hardness and wear resistance in comparison with LMDed sample. The corrosion resistance decreased in the order of Q-IQ > Q-IQ-T > LMDed samples in 3.5 wt-% NaCl solution.