Kazutomo Hoshino

Diffusion of titanium in copper

Interdiffusion coefficients in copper-titanium alloys have been determined by Matanos method in the temperature range between 973 and 1283 K on (pure Cu)-(Cu-1.98 at. pct Ti alloy) and (pure Cu)-(Cu-2.91 at. pct Ti alloy) couples. Temperature dependence of the impurity diffusion coefficient of titanium in copper, determined by extrapolation of the concentration dependence of the interdiffusion coefficient to zero mole fraction of titanium, is expressed by the following Arrhenius equation along with the probable errors:DTi/Cu=(0.693−0.135+0.169)×10−4exp[−(196±2)kJ mol−1/RT] m2/s.The difference in the activation energies for the impurity diffusion of the 3d-transition metals and self-diffusion in copper has been calculated by applying LeClaires model with the oscillating potential of the impurity atom in copper. The calculated values agree well with the experimental values including the present one.

Diffusion of vanadium, chromium, and manganese in copper

The diffusion coefficients of vanadium, chromium and manaanese in copper have been determined by the residual activity method with radioactive tracers V48, Cr51 and Mn54 in the temperature ranges between 955 and 1342 K, between 999 and 1338 K and between 971 and 1253 K, respectively. The temperature dependence of the diffusion coefficients is expressed by the following Arrhenius equations along with the probable errors:DV/Cu = (2.48-0.44+0.53) x 10−4 exp [-(215 ± 2) kJ mol−1/RT] m2 per s,DCr/Cu = (0.337-0.090+0.124) x 10−4 exp [-(195 ± 3) kJ mol−1/RT] m2 per s,DMn/Cu = (1.02-0.18+0.22) x 10−4 exp [-(200 ± 2) kJ mol−1/RT] m2 per s.Anomalous penetration profiles for the diffusion of Cr51 and Mn54 in the present results suggest that experimental results onDCr/Cu andDMn/Cu in the past have been influenced by oxidation and evaporation of the chemically active radiotracers during annealing for diffusion.

A simple model for the melting of fine particles

Abstract The size dependence of the melting temperature of fine particles is discussed, on the basis of the Debye model and the Lindemann law, by phenomenologically taking into account surface phonon softening.

Solute enhancement of self-diffusion of copper in copper-tin, copper-indium and copper-antimony dilute alloys

Abstract The self-diffusion coefficients of copper in copper-rich Cu-Sn, Cu-In and Cu-Sb solid solutions containing up to 3 at.% Sn, 3 at.% In and 1.7 at.% Sb, respectively, in the temperature range between 1005 and 1145 K have been determined by the serial sectioning method with radioactive tracer 64Cu. It has been found that enhancement of the self-diffusion coefficient of Cu by addition of Sn, In and Sb is expressed by a quadratic equation of the solute concentration rather than a linear one. Combining the enhancement factor of solvent diffusivity determined by the present work with the previous experimental data on the vacancy flow factor determined by the measurement of Kirkendall effect, an appropriate numerical set of the correlation factor and the jump frequency ratios in the five-frequency model have been evaluated. The correlation factor for the impurity diffusion of Sn, In and Sb in Cu thus obtained is in the range between 0.1 and 0.2 in the temperature range between 1005 and 1089 K. Such a small value of the correlation factor suggests highly correlated jumps of a solute atom to a vacancy.

Interdiffusion and Kirkendall effect in Cu—In alloys

Abstract Interdiffusion coefficients, [Dbar], in Cu-rich Cu—In solid solutions containing less than 7 at.% In have been determined by Matanos method in the temperature range 949–1119 K using semi-infinite diffusion couples consisting of pure Cu and Cu—In alloys with Kirkendall markers. From the interdiffusion coefficient and the Kirkendall marker shift, the intrinsic diffusion coefficients of In and Cu, D In, and D cu, have been determined for the compositions at the marker positions, 0·9, 1·7, 2·9 and 4·6 at.% In. The intrinsic diffusion coefficients in dilute alloys containing less than 2 at.% In have been determined by Heumanns method using thin-plate couples. In both types of the couples (semi-infinite and thin plate), it has been found that the Kirkendall marker moves towards the In-rich side and that the ratio of D In/D cu is about three. Using the values of the tracer diffusion coefficients of In and Cu in pure Cu and the value of the intrinsic diffusion coefficient of Cu extrapolated to the infi...