The diffusion of hydrogen in liquid Ni,Cu, Ag,and Sn

The rates of absorption of hydrogen in stagnant liquid Ni, Cu, Ag, and Sn have been measured using 1) an unsteady-state gas-liquid metal diffusion cell technique similar to that used by El-Tayeb and Parlee for iron and 2) a steady-state diffusion cell technique recently developed in this laboratory. The rates of absorption are considered to be controlled by diffusion in the liquid. On this basis the chemical diffusion coefficients of hydrogen (D _H) in liquid Ni, Cu, and Ag, calculated from the rate data, can be described by:D _H ^Ni =7.47×10^?3 exp(?8550±1114/RT) cm²/secD _H ^Cu =10.91×10^?3 exp(?2148±349/RT) cm²/secD _H ^Ag =4.54×10^?2 exp(?1359±207/RT) cm²/sec In the above equations, the uncertainty in the activation energy (Q _H) corresponds to the 90 pct confidence level. No reliable Arrhenius equation could be obtained forD _H ^Sn , but theD _H values in tin are greater than for the other three metals. The following interesting and possibly significant correlations are observed betweenD _H,Q _H, and the hydrogen solubility (S _H):D _H ^Ni <D _H ^Fe <D _H ^Cu <D _H ^Ag <D _H ^Sn , andQ _H ^Ni >Q _H ^Fe >Q _H ^Cu >Q _H ^Ag , andS _H ^Ni >S _H ^Fe >S _H ^Cu >S _H ^Ag >S _H ^Sn .