CONSOLIDATION OF AL85NI10MM5(MM-MISCHMETAL) AMORPHOUS POWDERS BY WARM EXTRUSION

Al-Ni-Ln(Ln: lanthanide metal) amorphous alloys with high strength have attracted attention as a structural light metal. The practical use of the amorphous alloys requires the development of a consolidation technique into a bulky form with full density. The effects of extrusion temperature, reduction in cross-sectional area (RA) and construction of billet on the degree of consolidation and structure of extruded bulks were examined for Al85Ni10Mm5 (Mm: mischmetal) amorphous powders produced by high pressure gas atomization. In the case of an ordinary billet, the resulting bulks consist of crystalline phases with full density because of the difficulty of the suppression of crystallization during extrusion. On the other hand, by using a billet with an appropriate core, an amorphous bulk with full density was obtained. The high degree of consolidation in the case of the core billet is presumably because of the generation of a high pressure leading to full density even at a small RA and the effective utilization of large shear stress generating at the outside part of the billet. The compressive strength of the Al85i10Mm5 amorphous bulk produced by the use of the core billet reaches 900 MPa which is the same as the tensile fracture strength of the melt-spun Al85Ni10Mm5 amorphous ribbon.