Tomoshi Takahashi

Diffusion of zinc in commercial Al-Zn alloys under high pressure

The effective interdiffusion coefficients of zinc in commercial Al-Zn alloys are obtained within the temperature range 773 to 883 K under pressures from 0 to 0.41 GPa. From the temperature dependence of the effective interdiffusion coefficients, the activation energies for the 701, 703 and 705 alloys are evaluated to be 125, 124 and 127 kJ/mol respectively, and their pre-exponential factors are 3.0 × 10−5, 4.0 × 10−5, and 3.9 × 10−5 m2/s respectively. The activation volumes, ΔV, for diffusion of zinc in the commercial Al-Zn alloy are 8.30 × 10−6, and 8.60× 10−6 m3/mol at 823 and 883 K, respectively. The ratios of the activation volume to the molar volume of aluminum, ΔV/V0, are 0.83 at 823 K and 0.86 at 883 K. This means that the diffusion of zinc in the commercial Al-Zn alloys occurs predominantly by the monovacancy mechanism at 823 and 883 K.

Interdiffusion in the copper-rich solid solutions of Cu-Ga and Cu-Mg alloys

Determination des coefficients dans les domaines 0 a 13,4 at% Ga (0 a 4,5 at% Mg) et 1003 a 1203 K (968 a 1098 K)

Effect of high pressure on interdiffusion in Cu-Zn alloys at temperatures near the melting point

Interdiffusion of copper and zinc alloys of Cu-28.5 at. pct Zn and Cu-4.9 at. pct Zn has been investigated under pressures from 0.101 to 3240 MPa in the temperature range from 1256 to 1377 K. The diffusion coefficients decrease with increasing pressure. The activation energy for impurity diffusion of zinc in copper increases with pressure. The ratio of the activation volume to the molar volume of copper is between 0.75 and 0.90. It is concluded that the impurity diffusion of zinc in copper occurs predominantly by the monovacancy mechanism at temperatures near the melting point of the alloy.

Interdiffusion inα solid solutions of the Cu-Zn-Sn system

AbstractThe interdiffusion coefficients in the α f c c phase of Cu-Zn-Sn alloys,

Interdiffusion in Co Solid Solutions of Co-Al-Cr-Ni System at 1423 K

\tilde D_{SnSn}^{Cu} , \tilde D_{SnZn}^{Cu} , \tilde D_{ZnZn}^{Cu} and \tilde D_{ZnSn}^{Cu}

Ternary diffusion and thermodynamic interaction in the β solid solutions of Ti–Al–Fe alloys at 1423 K

, have been determined at 1073 K. The concentration profiles indicate that the diffusion rate of tin is greater than that of zinc in the Cu-Zn-Sn alloy. The diffusion paths show the typical S-shaped curves. All of the four interdiffusion coefficients are positive and they are very sensitive to the solute concentration. The atomic mobilities of the three diffusing elements in Kirkendall planes increase in the order of Cu, Zn, Sn. The interaction energy of the Cu-Sn bond is much larger than that of the Zn-Sn bond. From the results of the present work it seems that the Onsager reciprocal relation holds in the a phase of the Cu-Zn-Sn system.

Interdiffusion in the aluminium-rich solid solution of Al-Cu alloys

Quaternary interdiffusion experiments of Al-rich α Al-Zn-Mg-Cu alloys have been performed in the temperature range from 755 to 833 K. The concentration profiles indicate that the diffusion distance of Cu is shorter than those of Zn and Mg in the solid solutions. The direct interdiffusion coefficients D 4 ZnZn , D 4 MgMg and D 4 CuCu are positive, and indirect coefficients are negative. The impurity diffusion coefficients of Zn (or Cu) in Al-Cu(or Zn) -Mg alloys can be expressed by the follwing equations. D * Zn(Al-Cu-Mg) =3.9 × 10 -5 exp (-124 kJ mol -1 /RT -1 ) m 2 /s, D * Cu(Al-Zn-Mg) =5.7 ×10 -5 exp (-132 kJ mol -1 /RT -1 ) m 2 /s. From the ratio values of indirect coefficient to direct one, it is expected that attractive interactions of Zn-Mg, Zn-Cu and Cu-Mg atoms exist in the Al-Zn-Mg-Cu alloys.