Experimental high-throughput approaches based on diffusion couples in reaction crucibles recently have been successfully introduced in the research of magnetic materials. However, sometimes this method is limited out of thermodynamic and kinetic reasons, e.g. when melting point reduction does not occur. Liquid and solid state reaction sintering is an advanced powder based approach suited for (1) discovering novel phases, (2) verifying and specifying phase equilibria in systems with existing information and (3) realization of phases difficult to obtain by conventional metallurgy. Therefore, reaction sintering delivers significant contribution for accelerated materials discovery and development in the research of magnetic materials.
The aim of this study was to design a vitrification method suited to field embryo transfer experiments in goat. In a first experiment, a standard vitrification protocol, previously designed for sheep embryos was compared to slow freezing of goat embryos. No significant difference was observed on kidding rate (48% versus 69%, respectively), nor on embryo survival rate (35% versus 45%). Second experiment: all embryos were vitrified. After warming, embryos were either transferred directly (direct transfer), or after in vitro dilution of the cryoprotectants (conventional transfer). The kidding rate was not affected by the transfer method (38% versus 23%, respectively). However, embryo survival rate tended to be higher after direct transfer (26% versus 14%). Third experiment: OPS vitrification was compared to standard vitrification. The kidding rate was not affected (22% versus 39%, respectively), but the embryo survival rate was lower after OPS (14% versus 28%). Fourth experiment: 0.4 M sucrose was added with cryoprotectants in vitrification. The kidding rate after direct transfer was significantly enhanced after addition of sucrose (56% versus 27%, respectively), whereas embryo survival rate was not significantly affected (32% versus 18%). Fifth experiment: vitrification with sucrose supplementation was compared to slow freezing. No significant difference was observed after direct transfer on kidding rate (52% versus 31%, respectively), but embryo survival rate tended to be higher after vitrification (34% versus 21%). In conclusion, our results indicate that addition of 0.4 M sucrose in association with direct transfer improves significantly the viability of goat vitrified embryos.
Cemented carbides are hard and tough materials for cutting tool, consisting of micrometer-sized carbides embedded in a ductile metal binder phase. In order to increase the performance and extend the service lifetime of the cemented carbides, graded cemented carbides have been developed. The formation of gradient zone during liquid phase sintering is a diffusion-controlled process, and knowledge of diffusivity is indispensable to understand formation mechanism, optimize technological parameters and design a new type of graded cemented carbides. In this paper, a diffusion database for multi-component C–Co–Cr–W–Ta–Ti–Nb–N cemented carbides has been developed through a combination of experiment, theoretical analysis and assessment. The diffusion database contains the atomic mobility parameters for different diffusing elements in liquid and fcc phase. The atomic mobility parameters in liquid phase are theoretically calculated by the newly modified Sutherland equation, and the atomic mobility parameters in fcc phase are optimized by the diffusivities measured in the present work and from the literature. In conjunction with the thermodynamic database for cemented carbides (CSUTDCC1: Central South University Thermodynamic Database for Cemented Carbides—version-1), the diffusion database (CSUDDCC1: Central South University Diffusion Database for Cemented Carbides—version-1) can be used to simulate the gradient sintering process. Simulations of different kinds of graded cemented carbides are presented using the databases and compared where possible against experimental data, in order to validate its accuracy.