Fabrication of large-size Fe-based glassy cores with good soft magnetic properties by spark plasma sintering

Abstract

Glassy Fe65Co10Ga5P12C4B4 alloy powders with a large supercooled liquid region of 50 K before crystallization were synthesized in the particle size range below 125 μm by Ar gas atomization. With the aim of developing a large-size Fe-based glassy core with good soft magnetic properties, the consolidation method of spark plasma sintering was applied to the Fe65Co10Ga5P12C4B4 glassy powders. The existence of the supercooled liquid region enabled us to form a large-size glassy alloy disc 20 mm in diameter and 5 mm in thickness with a high relative density of 99.7% at the glass-transition temperature of 723 K and under the external applied pressure of 300 MPa. The resulting glassy core of 18 mm in outer diameter, 10 mm in inner diameter, and 4 mm in thickness exhibits good soft magnetic properties: 1.20 T for saturation magnetization, 6 A/m for coercive force, and 8900 for maximum permeability. The good soft magnetic properties of the Fe-based bulk glassy core are attributed to the combination of the high relative density and the maintenance of the single glassy structure.

Iron-based bulk metallic glasses

“…magnetostriction and coercivity. For example, it has been shown that the saturation magnetisation of the alloys is not any different whether measured on the melt-spun ribbon form or powder 235 or between the melt-spun ribbon and bulk rods of different diameters. 101 These are illustrated in the hysteresis loops presented in Fig.…”

Bulk Glassy Fe–Mo–Ga–P–C–B–Si Alloys with High Glass-Forming Ability and Good Soft Magnetic Properties

“…The stable supercooled liquid with high internal equilibrium state is very important for utilizing the viscous flowability in the supercooled liquid state at the powder sintering process. 13,14,17) The heating and cooling behaviors were investigated by DTA. Figure 2 shows DTA curves of the Fe 77Àx Mo xGa 3 P 10 C 4 B 4 Si 2 (x ¼ 1, 2, 4, and 6) alloys.…”

“…With the aim of synthesizing large size Fe-based BGAs with high I s , we developed Fe 65 Co 10 Ga 5 P 12 C 4 B 4 and Fe 77 Ga 3 P 9:5 -C 4 B 4 Si 2:5 BGAs which exhibit the high I s of 1.2 and 1.35 T, as well as large ÁT x of 45 and 50 K, respectively, 11,12) that allowed us to synthesize Fe-based BGAs successfully with diameters up to 20 mm by the consolidation method utilizing significant viscous flowability in the supercooled liquid state. 13,14) As the size is not enough yet for applications of the magnetic cores used for motor engine, etc., it is necessary to synthesize new Fe-based ferromagnetic BGAs with high I s , large GFA and large ÁT x which is need for crystallization suppression at powder sintering process.…”

Densification of Gas Atomized Ni-Based Metallic Glassy Powders by Spark Plasma Sintering

“…Hence the SPS process can be applied to materials that need suppress crystallization and grain growth. Using the SPS process, Zr-based, 20) Cu-based, 21) Fe-based, 22) and Ni-based 23) BMG specimens have been fabricated. In the present study, the gas-atomized Ni 52:5 Nb 10 Zr 15 -Ti 15 Pt 7:5 metallic glassy alloy powders were sintered by the SPS process at various sintering temperatures.…”