Peng Zhou

Isothermal sections of the Co–Ni–Ti system at 950 and 1 000 °C

Abstract The isothermal sections of the Co–Ni–Ti system at 950 and 1 000 °C were investigated experimentally. Diffusion couples were measured by electron probe microanalysis to construct the phase relations at 950 °C, whereas eleven key alloys annealed at 1 000 °C were investigated using X-ray diffraction and electron probe microanalysis. The ternary phase, τ-(Co,Ni)3Ti (hP24-VCo3), was observed at both temperatures. At 950 °C, continuous solid solutions are formed between CoTi2 and NiTi2 as well as between CoTi and NiTi. Eight 3-phase regions, i. e. Ni3Tiu2009+u2009(Co,Ni)Tiu2009+u2009τ, Ni3Tiu2009+u2009γ-(Co,Ni)u2009+u2009τ, τu2009+u2009c-Co2Tiu2009+u2009(Co,Ni)Ti, τu2009+u2009c-Co2Tiu2009+u2009Co3Ti, τu2009+u2009Co3Tiu2009+u2009γ-(Co,Ni), c-Co2Tiu2009+u2009h-Co2Tiu2009+u2009Co3Ti, Lu2009+u2009β-(Ti)u2009+u2009(Co,Ni)Ti2 and Lu2009+u2009(Co,Ni)Ti2u2009+u2009(Co,Ni)Ti, were constructed at 1 000 °C. Considerable ternary solubilities in Ni3Ti, Co3Ti and c-Co2Ti were determined.

Developing Cemented Carbides Through ICME

The ICME (Integrated Computational Materials Engineering) for cemented carbides aims to combine key experiments with multi-scale simulations from nano (10−10~10−8 m) to micro (10−8~10−4 m) to meso (10−4~10−2 m) and to macro (10−2~10 m) during the whole R&D process of cemented carbides. Based on ICME, the framework for R&D of cemented carbides, involving end-user demand, product design and industrial application, is established. In this work, a description to our established thermodynamic and thermophysical (diffusion coefficient, interfacial energy, and thermal conductivity and so on) databases is presented, followed by simulation of microstructure evolution during sintering of cemented carbides by means of phase field method. Work is also done to investigate the correlation between microstructure and mechanical properties (crack, stress distribution, and coupled temp-displacement) by using phase field and finite element methods. The proposed ICME for cemented carbides is used to develop a few new cemented carbides (including double layer gradient cemented carbides and γ′-strengthened Co–Ni–Al binder cemented carbides), which have found industry applications.