Deformation mechanisms underlying tension-compression asymmetry in magnesium alloy ZK60 revealed by acoustic emission monitoring

This study is aimed at clarifying the microscopic mechanisms that determine a pronounced asymmetry of plastic deformation with respect to tension and compression in magnesium alloys, even having a random texture. The specific object of the present investigation is the Mg-Zn-Zr alloy ZK60. The mechanisms in question are based on a synergistic interplay between dislocation slip and deformation twinning. The details of the relative contributions of these principal processes were studied by monitoring the acoustic emission (AE) underpinned by robust AE signal classification developed recently. Through the cluster analysis of AE time series in spectral domain, the sequences of the predominant deformation mechanisms were identified for early stages of cyclic loading with opposite directions of the first loading excursion into tension or compression.