Atomic force and magnetic force microscopics applied to duplex stainless steels

Atomic and magnetic force microscopies (AFM and MFM, respectively) were employed to study the topographic features and magnetic patterns in "duplex" stainless steels (DSS). High coercivity (HC) and low magnetization (LM) tips were used in the magnetic characterization. Different tip-surface separations were explored, varying from 5 to 200 nm. Topographic features were observed together with magnetic domains for tip-sample separations up to 30 nm. For distances above this value, one cannot see more any evidences of topography, and magnetic domains can just be visualized. When the tip-sample separation attained 200 nm, the magnetic forces could not be detected and the magnetic image was lost. The results showed that distinct magnetic patterns could be observed depending on the magnetic-coated tip used. LM tips came more appropriate to the magnetic characterization of soft magnetic materials such as DSS. (C) 2000 Elsevier Science B.V. All rights reserved.