Anelastic behavior under tensile and shearing stresses in bulk metallic glasses

It is known that an anelastic deformation occurs more remarkably for amorphous ribbon alloys than for crystalline metallic alloys by the tensile test. In addition, the result of the molecular dynamics simulation on tensile and shearing tests for Cu single component amorphous metal has indicated that the anelastic deformation occurs more remarkably under the shearing stress rather than under the tensile stress. In this report, tensile and torsional tests were actually performed for bulk metallic glasses to examine the difference in the anelastic behavior under shearing and tensile stresses. Single-phase bulk metallic glasses, La60Al20Ni10Cu5Co5, Pd40Cu30Ni10P20 and Zr55Cu30Ni5Al10 (at%), were chosen together with a steel, JIS SGD 400-D, as a representative of metallic crystals. The test specimens were a round bar shape and the diameters of a parallel gage section were 4 to 10 mm. No anelastic behavior was observed for the steel under tensile and shearing stresses. Although the metallic glasses did not exhibit distinct anelastic deformation under the tensile stress, the shearing stress mode leads to a significant anelastic deformation even at low stress level. The amount of the anelastic deformation increases with an increase in the shearing stress level.