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Effect of different rolling reductions on the microstructure and mechanical properties of Mg-6Al-3Zn-0.1Mn wt.% alloys were investigated by means of scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The results show that after rolling the as-extruded Mg-Al-Zn-Mn alloy, more second phases are dynamically precipitated. The grains are also gradually refined with increasing the total reduction due to the dynamic recrystallization, and the average grain sizes are estimated to be ∼7.2 μm, ∼3.7 μm, ∼1.2 μm for the as-extruded Mg alloy, ∼34% and ∼60% rolled samples, respectively. On the other hand, the high-density contraction twins have been activated in as-rolled Mg samples, which can effectively separate the Mg matrix and a similar grain refinement effect can be afforded. Moreover, the dislocations are significantly multiplied during the rolling process. Consequently, the tensile strength of the Mg alloy is gradually increased, and the ∼60% rolled Mg alloy exhibits the optimal mechanical properties, with the ultimate tensile strength (UTS) of ∼363 MPa and the elongation of ∼7.2%. • Ultra-fined grain size of ∼1.2 μm was produced in AZM630 alloy by combining extrusion and rolling. • The tensile yield strength of as-rolled Mg alloy is up to 327 MPa with high elongation of 7.2%. • Dislocation tangles and contraction twin boundaries effectively improved both the strength and ductility. [ABSTRACT FROM AUTHOR]

In this work, the neutron poison element of boron (B) has been successfully added into the AlNbTiZr based multiprincipal element alloy (MPEA) via the arc melting method, and a new class of nuclear fuel materials based on the MPEAs with both high strength, and neutron poison property has been developed. The mechanical results show that both the AlNbTiZr and AlNbTiZrB samples exhibit the high yield strength of 790 ~ 800 MPa under compressive condition, and 720 ~ 750 MPa under tension. With a minor addition of B element, the ductility of AlNbTiZrB sample is largely deteriorated, exhibiting the compressive ductility of ~ 35 % and tensile ductility of only ~ 1 %. The X-ray diffraction (XRD), Calculation of Phase Diagram (CALPHAD) and transmission electron microscopy (TEM) characterizations demonstrate the formation of numerous feather-like TiB precipitates in AlNbTiZrB sample, which lead to the largely deteriorated tensile ductility in B-containing sample. Despite of that, the compressive ductility can yet reach as high as ~ 35 %, and excellent yield strength can be also obtained. Consequently, the present B-containing MPEA can act as a new promising candidate for future nuclear-fuel materials. • A new boron-containing AlNbTiZrB multiprincipal element alloy (MPEA) has been successfully developed. • AlNbTiZrB samples exhibit the high yield strength of ~ 800 MPa under compression, and also ~ 720 MPa under tension. • The poor tensile ductility in AlNbTiZrB can be ascribed to the existence of numerous feather-like TiB precipitates. • The present B-containing MPEA can act as a new promising candidate for future nuclear-fuel materials. [ABSTRACT FROM AUTHOR]

In this work, the trace Ce atoms have been added into the low-alloyed Mg-Al-Ca matrix, and the microstructure and mechanical properties have been investigated. For the Mg-Al-Ca ternary alloy, the tensile yield strength (TYS) would be decreased from ~ 321 MPa at 260 °C (extrusion temperature) to ~ 294 MPa at 290 °C. In contrast, the Mg-Al-Ca-Ce alloy can still exhibit the high YS of ~ 350 MPa and elongation of ~ 12.1% at higher extrusion temperature of 290 °C. Microstructure characterization shows that the Ce addition can effectively induce the solute segregations along both dislocations and grain boundaries in Mg-Al-Ca-Ce alloy, which thus leads to the finer grain size of 0.7 ~ 0.8 µm at a wide range of extrusion temperature. Formation of subgrain with strong texture, residual dislocations due to segregation and profuse nano-precipitations can together contribute to the high yield strength of Mg-Al-Ca-Ce alloy. More importantly, the trace Ce atoms can promote the activation of non-basal dislocations in Mg matrix and also the weakened texture in DRXed grains. As a result, the ductility is also simultaneously improved by the trace addition of Ce atom into Mg-Al-Ca based alloy. The relevant results can shed light on designing the new high strength and low-alloyed Mg alloys. • Simultaneous improvement of strength and ductility is achieved through trace Ce addition into dilute Mg-Al-Ca alloys. • Solute segregations along both dislocations and grain boundaries can be achieved by the addition of Ce. • Finer grain size of 0.7–0.8 µm at a wide range of extrusion temperature is obtained in the new Mg-Al-Ca-Ce alloy. [ABSTRACT FROM AUTHOR]