Strain hardening and tensile behaviors of gradient structure Mg alloys with different orientation relationships

Tension–Compression Yield Asymmetry Influenced by the Variable Deformation Modes in Gradient Structure Mg Alloys

“…Figure 3a shows the structure of the SMAT 0° sample. The region with 0.7 mm thickness can be further classified into two layers: The severely deformed layer, from the treated surface to the depth of 350 μm, showed an unresolved morphology due to the dramatically grain refinement [22]; and the medium deformed layer, from the depth of 350 μm to 700 μm, displayed remarkable deformation markings while the extent of grain refinement declined compared to the top layer. Subsequently, the layer from the depth of 700 to 1500 μm exhibited almost the same morphologies with the as-received HR alloy, implying remarkable attenuation of strain far away from the surface peening.…”

“…The XRD-measured PF at the depth of 700 μm after tension exhibited the c-axes maintained around the VA of the sample (Fig. 9a), corresponding to the effect of prismatic slip [19,22,28].…”

“…SMAT induces gradient magnitudes of strain and stress along the depths of the treated samples, thus causing structures with gradient features throughout the thickness [19][20][21][22]. For the different initial textures of the SMAT 0° and 90° samples, the different layers of the two samples displayed variable structural features, respectively.…”

“…Recently, gradient-structured (GS) metallic materials were developed based on the extensively studied nanostructured (NS) materials [16][17][18], exhibiting excellent combination of strength and ductility. Several researches [19][20][21][22] have manifested the advantages of gradient structure for improving the mechanical properties in commercial Mg alloys free of additive alloying elements, e.g., rare-earth elements. This provides a strategy to fabricate compositionally lean, low-cost Mg alloys with good balance of strength and ductility [23].…”

“…The gradient structure of Mg alloys produced by surface peening can be viewed as a pile of layers with gradually changed grain size and texture. Thus, mechanical properties of combinations of layers could vary with their thickness, resulting from the variable deformation modes operating in the different layers [19][20][21][22]. However, the previous works [19][20][21][22] mainly used uniaxial tensile tests to evaluate the mechanical behaviors of GS Mg alloys.…”