Rapid nickel diffusion in cold-worked carbon steel at 320–450 °C

Abstract

The diffusion coefficient of nickel in cold-worked carbon steel was determined with the diffusion couple method in the temperature range between 320 and 450 °C. Diffusion couple was prepared by electro-less nickel plating on the surface of a 20% cold-worked carbon steel. The growth in width of the interdiffusion zone was proportional to the square root of diffusion time to 12,000 h. The diffusion coefficient (D_Ni) of nickel in cold-worked carbon steel was determined by extrapolating the concentration-dependent interdiffusion coefficient to 0% of nickel. The temperature dependence of D_Ni is expressed by D_Ni = (4.5 + 5.7/−2.5) × 10⁻¹¹ exp (−146 ± 4 kJ mol⁻¹/RT) m²s⁻¹. The value of D_Ni at 320 °C is four orders of magnitude higher than the lattice diffusion coefficient of nickel in iron. The activation energy 146 kJ mol⁻¹ is 54% of the activation energy 270.4 kJ mol⁻¹ for lattice diffusion of nickel in the ferromagnetic state iron.

Keywords:

• diffusivity
• cold-work
• carbon steel
• vacancy diffusion
• low temperature

Acknowledgements

The authors wish to acknowledge the financial support of this work by Kansai Electric Power Co. Inc. The authors specially thank Prof. Roger W. Staehle for helpful suggestions, discussions, and encouragement. Careful and reliable experimental support by the staff at INSS, Dr. T. Yamada, Mr. K. Murakami, and Mr. M. Hirao is also gratefully acknowledged. The authors thank referees for their useful comments.

Disclosure statement

No potential conflict of interest was reported by the authors.