Formation of highly thermal stable Al88Ni6Y6 amorphous composite by graphene addition design

• A new Al-based amorphous composite with graphene (Gr) addition was fabricated.
• Moderate Gr addition benefits the amorphisation behavior of as-milled AlNiY powders.
• Gr addition obviously enhanced the thermal stability of Al-based amorphous composite.
• Special structure of Gr is important factor to explain ultrahigh thermal stability.

We study the effect of graphene (Gr) addition on the amorphisation and thermal stability of the Al88Ni6Y6 + x wt.% Gr (x = 0, 0.2, 0.5, and 0.8) alloys during mechanical alloying. The final milling-products consist of the amorphous phase and a few nanocrystals with face-centered cubic (fcc) structure, and the AlNiY(Gr) amorphous composites have been fabricated. We find that the 0.2 wt.% Gr addition obviously benefits the amorphisation and remarkably enhance the onset crystallization temperature of the alloy. Continuous heating transformation diagram shows that the as-milled Gr additional alloys need longer time than the Al88Ni6Y6 alloys to begin to transform into crystals, indicating the Gr addition design enhances the thermal stability of the as-milled Al88Ni6Y6 alloy. The influence mechanism of Gr addition has been discussed based upon the negative heat of mixing, atomic-size mismatch, diffusion-asymmetry, and special structure of Gr.

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