Invеstigation of mechanical stability of the АMA Fe82Nb2B14RE2 (RE = Y, Gd, Tb, Dy)

Abstract

The aim of study is to evaluate the mechanical properties of amorphous metallic alloys samples: Fe 84 Nb 2 B 14 , Fe 82 Nb 2 B 14 Y 2 , Fe 82 Nb 2 B 14 Gd 2 , Fe 82 Nb 2 B 14 Tb 2 , and Fe 82 Nb 2 B 14 Dy 2 after the temperature treatment. The investigated amorphous metallic ribbons were synthesized by melt spinning technique in helium atmosphere onto a copper wheel with a circumferential speed of about 30 m/s. Features of the technological process of Fe 82 Nb 2 B 14 RE 2 (where RE = Y, Gd, Tb, and Dy) amorphous ribbons producing cause the difference between their contact and external surfaces in mechanical properties. By X-ray diffraction method has been established that the Fe 82 Nb 2 B 14 RE 2 (RE = Y, Gd, Tb, and Dy) initial amorphous alloys have an amorphous structure. The microhardness of the samples in ribbon form has been measured by the use of Vickers technique. It shown the external side of the initial amorphous metallic alloys was characterized by higher the average microhardness than the contact side. It was established that base alloy of the Fe 84 Nb 2 B 14 after alloyed by the rare-earth elements (RE) increase microhardness on 0.85–1.90 GPa for contact surfaces and 3.04–3.89 GPa for external surfaces. The amorphous alloy Fe 82 Nb 2 B 14 Dy 2 has the highest value of microhardness (10.63–13.33 GPa) among alloyed initial samples. The difference between the mechanical properties of the both contact and external surfaces of the corresponding alloys decreases because of annealing at the nanocrystallization temperature. That could by explained by large number of clusters and the change of the free volume in the amorphous matrix of the alloys. The main influence on the mechanical properties causes annealing of ribbon samples in the air atmosphere because of changes of the AMА structure and formation of dense surface layers. Keywords: Amorphous metallic alloys, rare earth metals, thermal annealing, microhardness.