The effect of alloying on the microstructure and mechanical properties of Mo-Fe-B boride hard alloys

Mo2FeB2 based cermets with different Cr and Ni contents were prepared by liquid phase sintering. The effects of Ni and Cr content on the microstructure, hardness and fracture toughness were investigated. The results reveal that alloying of cermet with nickel leads to formation of structure сharacterized by high austenite volume fraction and low ferrite conten

Solving the problem of credit defaults in retail sector

The article analyzes dynamics of the volume and annual rate of loan delinquency of the country’s population for intermediate quarter dates, compares default retail credit portfolios with similar portfolio of organizations, and determines the main reasons for appearance of population’s debts before banks. It is concluded that it is necessary for banks to focus on development of their own tools and technologies of payment recovery, related to determination of early problematic debt for the purpose of taking preventive measures for preventing the appearance of past-due debts, which is possible under the condition of investing money assets into own analytical and technological tools. An approach to segmentation of debts and factors that could be used as indicators in the process of accompanying and servicing of credits are offered.peer-reviewe

Surface texturing of steel by femtosecond laser and accompanying structure/ phase transformations

Topography, structure, and phase composition of surface layers of AISI 321 stainless steel textured by 1030-nm 320-fs-laser pulses were studied by scanning electron microscopy and X-ray diffraction analysis. Variation in single-pulse fluence and the number of pulses was found to change the laser-produced surface texture from onedimensional quasi-periodic nanograting to microrelief of various roughnes

The formation of oxide layers on a titanium surface by irradiation with femtosecond laser pulses

By subjecting technical grade titanium to irradiation with femtosecond laser pulses with highenergy density, we create a microporous nanocrystalline oxide layer with a thickness of ∼50 μm on its surface. The structure and phase composition of the modified surface layers are studied using X-ray diffraction and high-resolution scanning and transmission electron microscopie

Formation of the oxide coating on the titanium surface by multipulse femtosecond laser irradiation

The effect of the femtosecond laser irradiation on the formation of oxide layers on the surface of a commercially pure titanium VT1-0 was studied. The methods of X-ray analysis, scanning electron and transmission electron microscopies were used to study the structural and phase state of oxide layers. As a result of the femtosecond laser irradiation, the porous multi-phase nanocrystalline oxide coating with a thickness of 50 µm is formed on the titanium surfac

Synthesis of pure hydroxyapatite by ion exchange reaction

An ion-exchange reaction for the synthesis of hydroxyapatite (HAP) in a constant alkaline medium using preliminary dry homogenization is proposed in this work. Sodium hydrogen phosphate Na2HPO4, calcium chloride CaCl2 and calcium hydroxide Ca(OH)2 were chosen as precursors. Studies carried out by methods of X-ray phase analysis, scanning electron and transmission microscopy showed that the material obtained is a singlephase hydroxyapatite powder with a Ca/P ratio close to 1.67. It was found that the particles of HAP powder obtained as a result of synthesis with subsequent washing have the shape of needles with a thickness of 10 to 40 nm and a length of 30 to 200 nm. Annealing of the powder at a temperature of 700 °C leads to agglomeration of particles, as well as to rounding of their shap

Investigation of the structural-phase state and its role in the formation of heat-resistance properties of 12% chromium steel

Results of investigations into the structural-phase state of EK-181 ferritic-martensitic low-activate steel after thermal treatment including quenching, intermediate tempering, and subsequent long tempering under loading at temperatures of 923 and 973 K are presentedye

The effect of composition and microstructure on hardness and toughness of Mo₂FeB₂ based cermets

Mo₂FeB₂ based cermets with various Ni, Cr and C concentrations were prepared. The effect of Ni, Cr and C on the phase composition and microstructure was investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and X-ray diffraction (XRD). Hardness (HRA) and fracture toughness (K1c) were also measured. It was found that nickel alloying leads to formation of two-phase state represented by Mo₂FeB₂ boride and austenite. Chromium alloying results in austenite to ferrite transformation and M₂₃C₆ and M₆C carbide precipitation in the case of carbon doping. Also, it was found that chromium influences the borides mean siz