The structure and properties of composites based on silver and aluminIum alloys strengthened with amorphous phase
Jan Dutkiewicz, Agata Kukuła-Kurzyniec, Lidia Lityńska-Dobrzyńska, Patrick Ochin
Quarterly No. 1, 2012 pages 44-49
DOI:
keywords: amorphous/crystalline composites, mechanical alloying, powder hot pressing, TEM
abstract Silver base composites intended for electric contact materials with additions of 20% of amorphous phases based on zirconium or nickel good glass formers were consolidated from ball-milled powders. The structure was investigated using X-ray diffraction and TEM. The consolidated samples show an increase in hardness with an amorphous phase addition which is of the order of 100 HV for 20% of the amorphous phase. SEM and TEM structure studies have shown a nanocrystalline grain size in silver after milling and nanocrystalline intermetallic inclusions in the amorphous phase after hot pressing. DSC studies have shown a crystallization peak, confirming amorphization of the powders. The composites have shown a similar loss of mass during 50 000 contact operations, like conventional Ag-W composites. Another type of additions used to form aluminum alloy base nanocomposites was the amorphous powder of the alloy Al10%Ni10%Ti10%Zr (in at.%). Almost complete amorphization was observed after 60 hours of milling. TEM investigations allowed us to identify nanocrystalline intermetallic phases in the milled powders. The microhardness of the powder was very high - near 500 HV. Similar to the other types of composites, some growth of aluminum solid solution grains was observed and only a slight increase in the size of intermetallic phases was noticed. The compression strength was slightly lower than for aluminum alloy based ceramic composites due to crack formation in the amorphous phase.