Nanostructure evolution, thermal stability and hardness of amorphous Al-Cu-Y (Co, La) (at.%) alloys

Al alloys with nominal composition of Al86Cu6Y6Co2, Al(86)Cu(6)Y(6)La(2 )and Al84Cu6Co2Y6La2 (at.%) were studied in as-spun and annealed states using differential scanning calorimetry (DSC), field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD) and microhardness. The effect of La and Co atoms and annealing temperature on enhancement of glass forming ability, thermal stability and hardness of Al-Cu-Y based alloys were investigated. The results show the amorphous Al84Cu6Co2Y6La2 alloy with higher RE (Y, La) contents and more elements is thermally stable up to 618 +/- 2 K while primary crystallization occurs. It also indicates the highest hardness of 378.1 +/- 15.3 HV which enhances even more to 394.2 +/- 16.8 HV after primary crystallization due to nano-sized alpha-Al crystals formation. The hardness of the alloy decreases to 340.3 +/- 16.4 HV after the second crystallization reaction, possibly because of the presence of some weak intermetallic compound, growth of the alpha-Al and crystallization of the amorphous matrix.

Automated summary

The properties of Al-Cu-Y based alloys containing La and Co atoms were studied, exhibiting thermal stability and increased hardness at 618 K. The hardness of the alloy increased after primary crystallization and decreased slightly after the second crystallization reaction.