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.

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

Effect of deformation twins on damping capacity in extruded pure magnesium

In this paper, two kinds of micro-tensile test systems for in-situ Electron Back-Scattered Diffraction (EBSD) are developed to explore the difference in microstructure evolution of AZ31 alloy under biaxial tensile stress state (BTSS) and uniaxial tensile stress state (UTSS). The in-situ EBSD results show that there is an apparent difference of texture evolutions during deformation under BTSS and UTSS and the different responses of tensile twins (TTs) in various stress states are proved to be the main reason. A modified calculation of Schmid factor (SF) for varied stress states further reveals that the distribution of TT SF on {0001} pole figure (PF) determined by BTSS significantly differs from that under UTSS. In addition, the change of stress states also affects the deformation compatibility of TT to slip systems. The poor formability of Mg alloy rolled sheets partly results from the incompatibility between TT and slip systems or tensile twinning under BTSS.

Influence of stress state on microstructure evolution of AZ31 Mg alloy rolled sheet during deformation at room temperature

Microyielding and damping capacity in magnesium

http://iopscience.iop.org/article/10.1088/1468-6996/15/3/035003/pdf

Detwining in Mg alloy with a high density of twin boundaries

for relationship between applied strain and cumulative AE counts during the anelastic recovery process was proposed. Therefore, AE is a promising method to study dynamic detwinning mechanism. The object of this study is to evaluate detwinning behavior during the tensile testing with twin-induced AZ31 Mg alloy by AE method. The texture evolution of the alloy during the tensile test was examined by electron backscatter diffraction (EBSD). The characteristics of the detwinning behaviors are discussed based on the results of AE analysis and microstructural features.

https://www.jstage.jst.go.jp/article/matertrans/53/9/53_MAW201218/_pdf

Takashi Yasutomi

Papers

In-Situ Evaluation of Detwinning Behavior in Extruded AZ31 Mg Alloy by AE