Tensile and compressive behavior of gold and molybdenum single crystals at the nano-scale

In situ mechanical tests were carried out to measure the tensile behavior of single-crystalline face-centered cubic (fcc) gold (Au) and body-centered cubic (bcc) molybdenum (Mo) nano-pillars with diameters between 250 and 1 μm, and to compare this with the compression results of these materials at the equivalent sizes. In Au, we observed similar tensile and compressive flow stresses at ∼10% strain although strain-hardening in tension is somewhat more pronounced than it is in compression. In Mo, the amount of strain-hardening in tension is significantly lower than that in compression, leading to a distinct tension–compression asymmetry in the flow stress at ∼5% strain. The dissimilarities between tensile and compressive behavior in both crystals are discussed in terms of sample geometry constraints and dislocation behavior in bcc crystals.