Effect of B, Si and Cr on the mechanical properties of Fe-based amorphous metallic ribbons

In this work, we present a systematic study about the effect of B and Si content on the mechanical properties of three melt spun amorphous alloy series: Fe92−xSi8Bx (10 ⩽ x ⩽ 18) – series 1, Fe90−xSi10Bx (10 ⩽ x ⩽ 18) – series 2 and Fe82−xSi10BxCr8 (12 ⩽ x ⩽ 20) – series 3. The Vickers microhardness increased as the B content was increased for all the series. On the other hand, the fracture strength, σTS, for series 1 exhibited a gradual increase as a function of B contents. In contrast, σST showed maximum values for series 2 and 3 at concentrations of 14 and 16 at.% B, respectively. In general, it was observed that the microhardness and strength of the alloy series with 8 at.% Si was higher compared with 10 at.% Si series. Studies of fractography by SEM revealed two types of fracture for the ribbons subjected to tensile tests: ductile for alloys with low B contents (⩽14 at.%) and brittle for both, alloys with high B contents (⩾16 at.%) and Cr-containing alloys. These variations of fracture type are used to explain the observed tendency for microhardness and tensile strength as a function of B content.