Magnetic properties of AISI 316L stainless steel doped with nanocrystalline Ti-B-C powders

Series of nanocrystalline TiC, TiB2, and B4C powders as dopants embedded in an AISI 316L austenitic steel have been prepared and investigated by magnetic measurements. The homogeneous composites with the dopants up to x = 7 vol% exhibit superparamagnetic properties, characterized by bifurcation between the field-cooled M-FC(T) and zero-field cooled M-ZFC(T) magnetization below T-ir and a maximum at T-max in low-field M-ZFC (7) curves. We found that the T-ir and T-max values depend proportionally on the dopant concentrations x. The magnetization measurements in fields above 1000 Oe suggested an induced phase transition from superparamagnetic state to ferromagnetic one but presumably without long-range magnetic correlation. An analysis of magnetic anisotropic energy barrier distributions implied that different sizes and compositional types of dopants may contribute to the superparamagnetic relaxation process. The results demonstrate possibility of obtaining new steelbased materials with desired properties and potential applications as combining magnetic and mechanical advantages.