Fabrication and Property of Amorphous/Nano Crystalline Al84Ni10Ce6 Bulk Alloy by a Powder Forging

The bulk Al84Ni10Ce6 alloy was fabricated by a powder forging process. The process involved pre-compaction of amorphous powder by cold pressing and subsequent isothermal forging at temperatures from 523 to 823K with the strain rate of 10-2 s-1. The porosity decreased rapidly with increasing forging temperature up to 648K, and a fully dense bulk specimen with the porosity less than 1% was achieved when the forging was carried out at and above 648K. TEM observation on the fully dense bulk alloys revealed a mixed structure consisting of nano-scaled crystalline particles and amorphous matrix. It was also revealed that the size and volume fraction of the crystalline phases increased with increasing forging temperature. Noticeably high compressive fracture strength of 1355MPa and Vickers hardness number of 530 were obtained at room temperature for the fully dense bulk specimen forged at 648K, which contains the refined crystalline particles (average size: 28nm, volume fraction: 44%) in an amorphous matrix.