Measurement of Elastic Constants on Nanostructured Iron and Copper

Abstract

Measurements of the elasticity modulus and Poisson’s ratio on nanostructured iron obtained by mechanical milling and on nanostructured copper obtained by severe plastic deformation (ECAP) have been carried out. Iron powder was severely deformed in a planetary ball milling. Powder compaction was done in a testing machine, obtaining cylinders that were compacted at temperatures between 425°C and 500°C. Commercial Cu of 99.98 wt % purity was processed at room temperature by Equal-Channel Angular Pressing (ECAP) following the route Bc. Heavy deformation was introduced in the samples after a considerable number of ECAP passes, from 1 to 16. A significant grain refinement was observed after processing the samples. The most important microstructural and mechanical changes were introduced in the first ECAP pass. Elasticity modulus and Poisson’s ratio were determined in iron and copper samples by ultrasonic measurement using an ultrasonic pulser-receiver and two transducers appropriate to the tested materials for pulse-echo sound velocity measurement in longitudinal and shear modes.

Can Young’s Modulus of Metallic Alloys Change with Plastic Deformation?

“…4 shows an image of osciloscope in which appears the intensity of signal versus time for the corresponding alloys. A high signal attenuation was achieved and it was not due to the intrinsec magnetic properties of this material, because this attenuation effect not occurs in another magnetic materials, as for example iron prepared in a similar form [15].…”

“…Roca et al [15] measured by ultrasounds the elasticity modulus and Poisson's ratio on nanostructured iron obtained by mechanical milling and on nanostructured copper obtained by severe plastic deformation (ECAP). Results obtained in iron seems indicate that the porosity was not the dominant microstructural effect in the behavior of the elasticity modulus.…”