Consolidation and Structure Formation during the Sintering of Composites Based on Nitrides of Transition Metals of Groups IV-V. Part IV. Sintering of Composite Materials of (VN, TaN) ― Ni
A study is made of the sintering of (VN, TaN) ― Ni composites in argon under isothermal and nonisothermal conditions. It is shown that the sintering of these materials is characterized by a reaction between the components, which is accompanied by the release of nitrogen from the nitrides and the formation of solid solutions and intermetallides based on nickel. These processes affect the rate and sign of the consolidation process. It is established that nitrides of vanadium and tantalum are sintered with nickel considerably more rapidly and at a lower temperature than nitrides of group-IV transition metals. Isothermal sintering leads to a slowing of consolidation compared to nonisothermal sintering, which can be attributed to the release of nitrogen from the nitrides and its localization in closed pores. The sintering is accompanied by an increase in the volume content of the metallic binder and a change in its phase composition (intermetallides of nickel and nickel-based solid solutions form). TaN ― Ni materials are characterized by a solid phase with very fine grains (∼1 μm).