Characterisation of boride layer formed on Fe-Mo binary alloys

Abstract

The influence of molybdenum on the boronising behaviour of iron (with addition of 1, 2, 4, 8 and 16 wt-% Mo) was investigated by performing pack boronising at 1100 degrees C for 3 h. The borided samples were characterised using SEM-EDS, EPMA, XRD, microhardness tester and profilometer. FeB and Fe2B polyphase exists in all boronised pure Fe and Fe-Mo alloys. Mo2FeB2 precipitates were detected in the boride layer and transition zone. The increasing content of Mo in Fe-Mo alloys resulted in a decrease in the boride layer thickness. The average microhardness value of boride layers formed on pure Fe and Fe-16Mo alloys were measured as 1750 and 2050 HV, respectively, while approximate microhardness value of Mo2FeB2 precipitates was measured as 2600 HV. It was also observed that the increasing Mo content in Fe-Mo alloys resulted in an increment in the surface roughness from approximately 0.8 to 2.7 mu m.