Thermal stability, crystallization and soft magnetic properties of Fe-P-C-based glassy alloys

Thermal stability, crystallization and magnetic properties of Fe₈₀P₁₁C₉, Fe₈₀P₉B₂C₉, and Fe₇₇Al₃P₉B₂C₉ glassy alloys were investigated. The relationships of glass-forming ability (GFA) with thermal properties and crystallization, magnetic properties with crystallization were also discussed. The variation trend of GFA for these glassy alloys is in agreement with the reduced glass transition temperature. The annealing experiment shows that the primary precipitation phase both for the Fe₈₀P₁₁C₉ and Fe₈₀P₉B₂C₉ glassy alloys is α-Fe, and the addition of small amounts of Al is effective for suppression of the formation of α-Fe phase, resulting in the extension of supercooled liquid region and significant enhancement of GFA. The activation energy for primary crystallization calculated by Kissinger's equation indicates the addition of B in Fe–P–C alloy or Al in Fe–P–B–C alloy makes nucleation more difficult, which is responsible for the enhancement of GFA. In addition, it was found that the crystallized Fe₈₀P₉B₂C₉ specimen with ultrafine α-Fe grains exhibits high saturation magnetic polarization of up to 1.60 T and low coercive force of about 3.0 A/m.