In-situ Investigation of the Microstructure Evolution in Long-Period-Stacking-Ordered (LPSO) Magnesium Alloys as a Function of the Temperature

Abstract

Deformation behavior of two Mg-Zn-Y magnesium alloys, having a different fraction of the long-period-stacking-ordered (LPSO) phase, has been investigated at room temperature and 200 • C by a combination of in-situ neutron diffraction (ND) and acoustic emission (AE) measurements. The results indicate that the twinning in the magnesium matrix and the kinking in the LPSO phase strongly depend on the composition of the material and the testing temperature. Further, active deformation mechanisms and particularly the load transfer from the magnesium matrix to the LPSO phase define the mechanical properties of the investigated alloys.

Effect of Extrusion Ratio in Hot-Extrusion on Kink Deformation during Compressive Deformation in an αMg/LPSO Dual-Phase Magnesium Alloy Monitored by <i>In Situ</i> Neutron Diffraction

“…A loading machine was aligned with the loading axis becoming horizontal and 45 degrees to the incident beam. The detailed alignment of the loading machine and the specimen can be found elsewhere [18,20,28,29].…”

“…In situ neutron diffraction during loading is well known to be a powerful method to understand deformation behavior of the individual phases in multiphase materials [18][19][20][21][22], including deformation slips and twinning in magnesium alloys [23][24][25][26][27][28][29][30]. In our previous report [31], the in situ neutron diffraction during tensile loading up to the specimen fracture was performed using three kinds of samples of Mg97Zn1Y2 alloy: a cast sample (As-Cast), hot extruded samples with the R values of 5.0 (R=5.0) and 12.5 (R=12.5).…”

Stress Evaluation Method by Neutron Diffraction for HCP-Structured Magnesium Alloy

“…The loading axis was aligned 45 • horizontal to the incident beam. The details on the alignment can be found elsewhere [11,14,19,26,27]. Using a pair of 90 • scattering detector banks in TAKUMI, the diffraction pattern with the scattering vector parallel to the loading axis that, hereafter, is referred to as the loading direction (LD), and perpendicular to the loading axis that, hereafter, is referred to as the transverse direction (TD) was simultaneously collected.…”

“…The IPF were obtained from the Rietveld-texture analysis [32,33], assuming a fiber texture, using the twelfth-order spherical harmonic function implemented in the MAUD software, v. 2.78 [34]. The values of multiple random distributions (mrd) are large near the [10.0] pole, displaying that a typical basal texture with the c-axis orthogonal to the extrusion direction [12,19,26,35,36] was developed. The condition of the IPF, in which the mrd values are large near the [10.0] pole, is kept even at the applied true strain value of 16.4%, i.e., the change in texture is small.…”