Interdiffusion of Bi in Liquid Sn

Abstract

The diffusion coefficients for the interdiffusion of Bi in liquid Sn were determined using the thin layer, long capillary technique. The effect of 0.5, 0.8, and 1.6 mm diameter capillaries on the apparent diffusion coefficient was investigated. For any temperature up to 600°C all three diameter capillaries yielded similar interdiffusion coefficients. At 700°C, the 1.6 mm diameter capillaries yielded concentration-penetration profiles that exhibited considerable scatter and abnormally high diffusion coefficients, indicative of the presence of convective mixing. At 800°C, both the 0.8 and 0.5 mm capillaries yielded considerable scatter in the concentrationpenetration profiles and abnormally high diffusion coefficients. Because of agreement of the results for both the 0.5 and 0.8 mm capillaries up to and including 700°C (and the 1.6 mm capillaries up to 600°C), it was concluded that the interdiffusion coefficients obtained are accurate for the temperature range 300 to 700°C with no significant contribution from buoyancy driven convection, capillary wall effects and/or Marangoni convection. The interdiffusion coefficient for the diffusion of Bi in liquid Sn can be represented by: D Sn Bi = 3:4%0:6 3 10 À8 È É exp [À 13; 600%1200=RT)]g m 2 =s: ð ÈThe results show that Bi diffuses in Sn at a slower rate than does Sn itself. In addition, it is possible that the interdiffusion coefficient may not be predicated on simple temperature dependence in at least some binary liquid metal systems, and that the diffusion coefficient may be affected by liquid/liquid phase transformations occurring at some temperature within the liquid.

Interdiffusion of Copper and Iron in Liquid Aluminum

“…Interdiffusion of Bi, Sb and Ag in Sn also give similar values for Q 0 . [22,34] Further, Ejima et al, [24] using the principle of corresponding states, have calculated that D 0 and Q 0 for solvent self-diffusion in Al are 1.03910 À7 m 2 /s and 23,000 J/mole respectively which are essentially identical to their values for the diffusion of Cu (and In) in Al.…”

“…[1] It has been noted that during the diffusion anneal some convective mixing may occur creating scatter in the experimental results but the mixing is localized and convective transport of solute along the length of the capillary is minimal not contributing greatly to the value of the diffusion coefficient. [22] The results of Jiao [27] are also included in Fig. 5.…”

“…The results of these studies have been reported by Cahoon et al [21] and Porth and Cahoon. [22] From these studies it was concluded that Bi diffuses more slowly in liquid Sn than does Sn itself, and Sb and Ag diffuse at very nearly the same rate in liquid Sn as does Sn.…”

Self-Diffusion in Liquid Copper, Silver, and Gold

“…An experimental study of diffusion properties in metal melts is a hard task. Progress in this field is connected with the arising of new techniques in the last two decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In particular, modern precise measurements provided a finding that small additions in dilute germanium weakly affect its diffusion coefficients in spite of the very big difference between their atomic mass [20].…”