Novel ${\hbox {Fe}}_{(97-{\rm x-y})}{\hbox {P}}_{\rm x}{\hbox {B}}_{\rm y}{\hbox {Nb}}_{2}{\hbox {Cr}}_{1}$ Glassy Alloys With High Magnetization and Low Loss Characteristics for Inductor Core Materials

Abstract

Fe-based glassy alloys with both high saturation magnetization and low magnetic anisotropy have attracted interest recently , and we have succeeded in developing novel glassy Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(97-x-y)</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> (x=5 -13, y=7-15) alloys for an inductor material with high corrosion resistance by added Cr is 1 at%. The glassy alloy series of Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(97-x-y)</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cr (x=5-13, y=7-15) have high glass-forming ability with wide range super-cooled liquid region of 29-37 K, large critical thickness of 110-150 ¿m, and low coercivity of 2.5-3.1 A/m caused by the structural homogeneity. The Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">77</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> glassy alloy exhibits the largest critical thickness of 150 ¿m related to the wide super-cooled liquid region of 36 K and the high saturation magnetic flux density (Bs) of 1.3 T, both of which are higher than those of the conventional amorphous Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">75</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> Cr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> alloy. The Fe-P-B-Nb-Cr powder/resin composite core has much lower core loss of 650 kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> which is approximately 1/3 lower than the conventional amorphous Fe-Si-B-Cr powder/resin composite core annealed at 623 K. Additionally, The Fe-P-B-Nb-Cr glassy alloy has higher corrosion resistance than other system glassy metal of Fe-Si-B-Nb-Cr by having a thick chromium passivation layer. the optimum annealing temperature of 623 K for these glassy alloys is lower than that (723 K) for the ordinary Fe-Si-B-Cr amorphous alloy, which is a significant advantage for the efficiency in mass production of inductor core using soft magnetic glassy alloy powder.