Unique metallurgical microstructures and characteristics of nano-amorphous state bulk alloys formed under high gravity by very high speed centrifugal casting

Abstract

ABSTRACTAn innovative “Rapid-Solidification Centrifugal Casting (RSCC) Process” was applied to manufacturing more high functional Fe-based magnetic alloys and some amorphous bulk metallic glassy alloys (BMGs) components. The molten alloys were poured into copper mold with rotation speed up to 6000rpm which can cause the maximum 4000 times as much centrifugal pressurization force as gravity. The bulk components of ring or very small three dimensional component samples of Fe and Zr alloy systems were successfully fabricated within only a few seconds at one process from melts with more cheap production cost. The molten raw BMG alloys (ZrAl system) and Fe-based soft-magnetic alloys(FeGaAl and FeSiB systems) by high frequency induction heating method were poured into copper mold. The fabricated BMG components of artificial tooth and ring of ZrAlNiCu alloy system are almost amorphous state by XRD profiles. Especially, the soft magnetic properties of two Fe-based alloys showed drastic change and were enhanced generally depending on the unique very fine, nano-scale columnar grains with strong texture toward radius direction for FeGaAl(Galfenol) alloy. The magnetization saturation Bs was enhanced up to1.97T in FeSiBPCu alloy. In consequence, according to synergistic effect of rapid solidification and high pressurization casting in this manufacturing process, RSCCP has the technical advantages of expansion of element composition, uniformity of the quality, reduction of internal defects and prevention of degradation at the time of secondary fabrication process of nano-crystalline-structured alloys and BMGs.