Gf Giel Bastin

The diffusion couple technique in phase diagram determination

The diffusion couple technique is a valuable experimental approach in studying phase relations in multicomponent systems. The use of different modifications of the method is illustrated by examples of phase diagram determination in various ternary systems. It is also shown that a number of error sources may appear when multiphase diffusion experiments are employed for constructing isothermal cross-sections. The difficulties connected with the concentration measurement at the interfaces and problems associated with the formation of a quasi-equilibrated diffusion zone are discussed. It is demonstrated that the efficiency of the diffusion couple technique is very high. However, in order to increase the reliability of the information obtained about a ternary diagram, a combination of the diffusion methods with an investigation of selected alloys is desirable.

Phase relations in the ternary TiNiz.sbnd;Cu system at 800 and 870 °C

Abstract We have investigated the isothermal cross sections through the ternary phase diagram Tiz.sbnd;Niz.sbnd;Cu at 800 and 870 °C by means of the diffusion couple technique. The results have been corroborated on essential points by the investigation of equilibrated alloys. Use has been made of optical, microprobe a nd X-ray analyses. The results differ from those mentioned in the literature. For two hitherto undescribed ternary intermetallic compounds X-ray diffraction data are given and crystallographic cell parameters are proposed.

On the diffusion of carbon in titanium carbide

AbstractThe chemical diffusion coefficient of carbon in TiC1-y was determined as a function of stoichiometry and temperature in the range between 1000 and 1600°C using the diffusion couple technique. In marker experiments carbon was found to be virtually the only diffusing component. Accurate carbon analyses were performed using EPMA, both in diffusion couples and in the carbides present in equilibrated alloys. The homogeneity region of TiC1-y in this temperature range and the concentration profiles were accurately determined. From these profiles it is immediately clear that the diffusivity of carbon is a function of the carbon concentration. The interdifussion coefficient { % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfKttLearuatLrhDLjhih9gDOL2yG0evae% XatLxBI9gBamXvP5wqSXMqHnxAJn0BKvguHDwzZbqegm0B1jxALjhi% ov2DaeHbuLwBLnhiov2DGi1BTfMBaebbnrfifHhDYfgasaacH8srps% 0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr0xc9pk0xbba9q8WqFfea0-yr% 0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dmeaabaqaci% GacaGaaeqabaWaaqaafaaakeaaiqGaceWFebGbaGaaaaa!3F06!

Diffusion of carbon in TiC1−y and ZrC1−y

\tilde D

Phase relations in the systems Fe-Ni-Mo, Fe-Co-Mo and Ni-Co-Mo at 1100 degrees C

} increases with decreasing carbon concentration and can be expressed by; { % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% GaaiikaGqaaiaa-rfacaWFPbGaa83qamaaBaaaleaacaWF0bGaeyOe% I0IaamyEaaqabaGccaGGPaGaeyypa0Jaai4waiaaicdacaGGUaGaaG% inaiaaiIdacaqGGaGaaeyzaiaabIhacaqGWbGaaeikaiaabMdacaqG% UaGaaeOmaGqaciaa+LhacaWFPaGaa8xxaiaa-bcacaWFLbGaa8hEai% aa-bhacaWFGaacdiGaa03eGmaabmaabaWaaSaaaeaacaWFZaGaa8xo% aiaa-vdacaWFWaGaa8hmaaqaaiaa+rfaaaaacaGLOaGaayzkaaGaae% iiaiaabogacaqGTbWaaWbaaSqabeaacaqGYaaaaOGaai4laiaa-nha% aaa!5B33!

An iterative procedure for the correction of secondary fluorescence effects in electron-probe microanalysis near phase boundaries

\tilde D(TiC_{t - y} ) = [0.48{\text{ exp(9}}{\text{.2}}y)] exp --\left( {\frac{{39500}}{T}} \right){\text{ cm}}^{\text{2}} /s