Laser cladding is a technology that uses high-energy-density lasers to quickly melt and solidify alloy powder on the surface of the metal substrate to form a cladding layer with good performance. The alloy powder composition has a significant impact on the cladding layer performance, including hardness, wear resistance and corrosion resistance. In this work, the effect of Nb content on the microstructure types and phase precipitation rules in the martensitic stainless steel laser cladding layers was investigated through the thermodynamics software. The martensitic stainless steel cladding layers with different Nb content was fabricated on the 45# steel substrate by the laser cladding. The microstructure and element composition of the cladding layers were analysed by the scanning electron microscope (SEM) and the energy spectrum analyser (EDS). The hardness, wear resistance and corrosion resistance of the cladding layers were also discussed. The results show that the amount of Cr element in carbide (boride) gradually decreases, while the amount of Nb element in carbide (boride) gradually increases, with the increasing Nb element content from 0.6 wt.% to 2.2 wt.%. For the performance of the cladding layer, the increase in the content of Nb makes the hardness and wear resistance of the cladding layer increase first and then decrease, but the corrosion resistance gradually increases. Generally speaking, the comprehensive performance is better when the Nb element content in the cladding layer is about 1.4 wt.%. At this time, the microhardness of the cladding layer is about 780.00 HV 0.2 , and the self-corrosion potential is -350.87 mV.

The addition of refractory metals represents a promising development approach for future high-entropy alloys (HEAs). Niobium and molybdenum are particularly suitable for increasing hardness as well as wear and corrosion resistance. In the context of surface protection applications, eutectic alloys with their homogeneous property profile are of particular interest. In the present work, two eutectic HEAs (EHEAs) were developed for the starting Al 0.3 CoCrFeNi using electric arc furnace. Following mechanical and microstructural characterization, the two alloys Al 0.3 CoCrFeNiMo 0.75 and Al 0.3 CoCrFeNiNb 0.5 were identified. For thermal spray processing, powders were prepared by inert gas atomization. The coatings produced by high velocity oxy-fuel (HVOF) spraying were characterized and evaluated comparatively to the castings, allowing process-structure-property relationships to be derived. Based on the results, statements on possible application potential can be made.

A bio-implant is a medical device used to support, replace or enhance a biological structure. Bio-implants have incalculable importance for mankind due to their crucial applications in situations like heart diseases, joint replacements, bone fixation and bone replacements etc. The materials which are used to manufacture bio-implants are generally called biomaterials. Corrosion and biocompatibility of biomaterials are the two issues, which are needed to be addressed to enhance the life span of the bio-implants. Various strategies were used to enhance the performance of biomaterials; however surface modification and alloying are the two main strategies among them. To employ these two strategies; various ceramic, metallic and composite materials were utilized as coatings and alloying elements with different biomaterials. Among all these materials, Niobium and Tantalum metals are studied by various researchers and proved to improve the corrosion resistance as well as biocompatibility of the bioimplants. This article gives a systematic overview of research work carried out in the area of bio-implants by utilizing Niobium and Tantalum for the enhancement of corrosion resistance and biocompatibility.

This paper presents the results of a study showing how isothermal aging affects the wear properties of Cr-Ni overlay alloy coatings with dispersed NbC particles. High Cr-high Ni coatings, with and without niobium carbides, were deposited on mild steel substrates via plasma transferred arc welding then age-hardened at temperatures from 773 to 1023 K. The precipitation behavior and wear properties of the coating samples were examined using Vickers hardness testing, SEM, TEM, EDX, XRD, and Ohgoshi wear testing. The results showed that isothermal aging significantly improved the hardness and wear resistance of the NbC-dispersed alloy but had little effect on the NbC-free samples. The difference in precipitation behaviors is probably due to the presence of niobium atoms in the alloy matrix, resulting in a continuous precipitation of α' phase.