Strengthening of aluminium based composites with amorphous metallic or Al2O3 particles
Agata Kukuła-Kurzyniec, Jan Dutkiewicz, Piotr Bobrowski, Wojciech Wajda, Anna Goral, Patrick Ochin, Loic Perriere
Quarterly No. 2, 2013 pages 141-146
DOI:
keywords: Al-based-amorphous composites, Al-based- Al2O3 composites, melt spinning, powder hot pressing, compression tests
abstract Aluminium alloy based composites were prepared by hot pressing in a vacuum in order to study the strengthening effect of an amorphous phase addition in the form of ball milled powder from melt spun ribbons of the Al73Si5Ni7Cu8Zr7 (at.%) alloy. For comparison, a composite with a strengthening ceramic Al2O3 phase was hot pressed under the same conditions. DSC measurements allowed the authors to determine the start of the crystallization process of the amorphous ribbons at 240°C. The presence of the majority of the amorphous phase in the melt spun ribbons was additionally confirmed by the X-ray diffraction technique which also revealed the presence of an α-Al solid solution and some peaks of intermetallic phases. SEM studies showed homogenous distribution of the strengthening particles in both kinds of composites and confirmed the existence of α-Al and some intermetallic crystallites inside the metallic amorphous particles. The hardness of all the prepared composites was comparable and amounted to approximately 50 HV1 for those with the Al matrix and 120 HV1 for the ones with the 2618A alloy matrix. The composites have shown a higher yield stress than the hot pressed aluminium or 2618A alloy. SEM studies of the cracks after compression tests revealed that the interfaces between the strengthening phase and matrix in metallic amorphous powder-Al /2618A alloy composites show a different character of the interface between the ceramic particles and the Al matrix. Therefore in the composite with the Al2O3 particles, cracks have the tendency to propagate at the interfaces with the matrix more often than in amorphous/Al composites.