Microstructure and compressive behavior of Al-base amorphous/nanocrystalline alloys fabricated by powder forging

Abstract

Al-base amorphous/nanocrystalline bulk alloy rods composed of Al–10Ni–6Ce (numbers indicate at.%) matrix alloy and Al–4Fe–0.6Mo–1.1V–0.3Zr alloy particles (volume fraction = 0.3) were fabricated by a powder forging process. The starting materials were rapidly quenched, powder-shaped amorphous Al–10Ni–6Ce alloy and nanocrystalline Al–4Fe–0.6Mo–1.1V–0.3Zr alloy. The amorphous alloy powders were prepared by the pulverization of melt-spun ribbons, and the nanocrystalline alloy powders were fabricated by using a gas atomization technique. The powder forging process involved pre-compaction of the amorphous/crystalline powder mixtures by cold pressing and subsequent forging at temperatures ranging from 623 to 773 K with a pressure of 0.66 GPa and a strain rate of 10 −2 s −1 to produce the rod-shaped bulk hybrid alloys having a diameter of 10 mm. Bulk monolithic Al–10Ni–6Ce alloys having the same shape were also fabricated by using a similar process to that used for the hybrid ones. Fully dense bulk rods with a porosity of less than 2% were achieved for all of the forged monolithic and hybrid alloys. A remarkably high compressive strength of about 1.2 GPa along with a compressive plastic strain of 1% was obtained at room temperature for the bulk hybrid specimen forged at 648–673 K. In contrast, the bulk monolithic specimen forged at 648–723 K did not exhibit any compressive plastic strain, although it possessed a very high compressive strength of approximately 1.34 GPa.