Honcharuk V. Influence of structural factors on the mechanical properties of high-strength composite materials based on refractory compounds

A systematic analysis of the mechanical behavior of WC-Co alloys was carried out (on alloys obtained under identical conditions, the influence of the size of particles of the WC matrix, the content of Co-binder and temperature on the complex of mechanical properties was studied). Mechanical characteristics were determined in a wide temperature range during bending tests. Three temperature intervals with different mechanisms of plastic deformation have been established. The temperatures of ductile-brittle transition of the investigated alloys, coefficients and indicators of strain hardening have been established. A physical interpretation of the results obtained is given. The experiment planning method (regression equation) established the dependences of the strength and crack resistance of the self-bonded SiC polyfraction composition on the size and ratio of fractions. It is shown that the maximum properties are realized in the two-fraction region. A model experiment was carried out and the healing of a crack at an elevated temperature under mechanical stress was studied. A technique for thermomechanical treatment of ceramic silicon carbide materials with the aim of increasing strength and crack resistance has been developed and theoretically substantiated. The behavior of the investigated composite materials is studied by the method of acoustic emission under mechanical loading. Two methods of non-destructive testing of the strength of the investigated materials by the AE method were developed and theoretically substantiated. A fundamental difference in the character of AE is shown in materials consisting only of brittle phases (SiC) and in a material containing a plastic phase (WC-Co). Key words: tensile strength, yield strength, plasticity before fracture, hard alloys, self-bonded silicon carbide, acoustic emission.