(1) Background: Boriding is one of the most common methods of thermal-chemical treatment due to its excellent hardness and wear resistance of the produced diffusion layers. However, it has limited application compared to carburizing and nitriding because of fragility and chipping. Introducing another alloying element into the boron media helps avoid those drawbacks and improve other surface properties of the layer. The purpose of this work is to improve the surface mechanical properties of L6 and 5140 low alloy steels by two-component surface hardening with boron and copper. (2) Methods: The treatment was performed by means of a powder-pack method using boron, copper, and aluminum powders in the following proportions: 60% B₄C + 20% Al₂O₃ + 16% CuO + 4% NaF. The time–temperature parameters of the treatment were four hours exposure at 950 °C. Microstructure, elemental, and phase composition were investigated as well as microhardness and wear resistance of the obtained layers. (3) Results: Layers of up to 180–200 μm thick are formed on both steels as a result of treatment. Needle-like structures similar to pure boriding was obtained. The maximum microhardness was 2000 HV on L6 steel and 1800 HV on 5140 steel. These values correspond to iron borides and were confirmed by XRD analysis revealing FeB, Fe₂B, and Cr₅B₃. The wear resistance of both steels was about ten times higher after the treatment compared to non-treated samples. (4) Conclusions: Surface hardening with boron and copper significantly improves the mechanical properties of both alloy steels. The results obtained are beneficial for different tribo-pair systems or three-body wear with abrasion and minimum impact loads.

The article considers the method of obtaining heterogeneous compounds using gradient transitions from intermediate materials. The results of studies of the structure of gradient transitions have shown the possibility of using additive manufacturing methods for obtaining products from heterogeneous metals and for the manufacture of functional gradient materials.

Research data for diffusion layers obtained on ARMCO Pure Iron samples in boron- and copper-containing powder mixtures are reported. The aim of this study aim has been to reveal the influence of copper content in a saturating mixture on the structure and thickness of the diffusion layer. In experiments, from 120- to 220-µm-thick diffusion layers with different structures have been obtained on ARMCO Pure Iron samples. It has been found that the thickness of the diffusion layer grows and its structure changes with increasing copper content in the saturating mixture.

The change in the dimensions of parts after diffusion saturation of alloyed steel 5KhNM with boron and copper is investigated. Diffusion layers obtained on samples with different compositions of the saturating mixture are described. It is shown that when carrying out experiments on saturation of samples in a medium of powders with boron and copper, diffusion layers with an acicular structure with a thickness of 220...330 μm are obtained, and the increase in the observed size was from 44 to 135 μm, depending on the composition of the powder mixture. The properties of diffusion layers have been studied, including the distribution of microhardness and chemical elements at different distances from the surface.