A Research on Surface Oxidation of Co67Fe4Cr7Si8B14 Amorphous Ribbon during Crystallization

مهندسی متالورژی و مواد

Article 6, Volume 24, Issue 2 - Serial Number 8, February 2014   

Document Type: Original Articles

DOI: 10.22067/ma.v24i2.28321

Authors

zahra jamili shirvan^* ; mohsen hadad sabzevar

Abstract

Deterioration of soft magnetic properties of amorphous ribbons happens when oxygen atoms diffuse in matrix during heat treatment. In this research, surface oxidation of Co67Fe4Cr7Si8B14 amorphous ribbons prepared by Planar Flow Melt Spinning (PFMS) process during crystallization was investigated.
In the first step, thermal stability of the ribbons was studied by Differential Thermal Analysis (DTA). Amorphous samples were then annealed isothermally in argon atmosphere with 0.2% oxygen for 30 minutes at the temperature range of 350-650 ºC with 50 ºC interval. Heat treated samples were studied by X-Ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analysis. According to the results, surface oxidation started around 550ºC. The oxide was found to be SiO2 with amorphous structure. An increase in the temperature up to 600ºC, no crystalline phases was recognized by XRD in the sample annealed at this temperature, which can be attributed to increasing the thickness and continuity of the oxide layer. For the temperatures above 600ºC, the instability and discontinuity of the oxide layer were observed in some areas. In these areas, oxygen diffused in the matrix and combined with cobalt as CoO, was also observed.

Keywords

Amorphous alloy; Co67Fe4Cr7Si8B14; Crystallization; Isoth00ermal annealing; Surface oxidation