On the effect of lattice disorders on the reversible magnetization process in pure nickel

Abstract

The reversible permeability was used to study the interaction behaviour of vacancies and dislocations with migrating domain walls under low magnetic fields in pure nickel. Increasing the dislocation density, by cold working, decreased the initial permiability and increased the coercive force. The observed inverse relationship between reversible permiability and plastic strain was explained on account of Kersten's theory of flexible domain walls. The increase in coercive force with dislocation density was attributed to the need for higher magnetic pressures to be exerted on domain walls to have them detached from the increased number of dislocation pinning points. Excess quenched vacancies caused the magnetic pressure on domain walls to leak out and higher fields were thus required to initiate Barkhausen jumps.