Microstructure,texture evolution and yield strength symmetry improvement of as-extruded ZK60 Mg alloy via multi-directional impact forging

Multi-direction impact forging(MDIF)was applied to the as-extruded ZK60 Mg alloy,and the microstructure,texture evolution and yield strength symmetry were investigated in the current study.The results showed that the average grain size of forged piece was greatly refined to 5.3μm after 120 forging passes,which was ascribed to the segmenting effect of{10–12}twins and the subsequent multiple rounds of dynamic recrystallization(DRX).A great deal of{10–12}twins were activated at the beginning of MDIF process,which played an important role in grain refinement.With forging proceeding,continuous and discontinuous DRX were successively activated,resulting in the fully DRXed microstructure.Meanwhile,the forged piece exhibited a unique four-peak texture,and the initial<10-10>//ED fiber texture component gradually evolved into multiple texture components composed of<0001>//FFD(first forging direction)and<11–20>//FFD texture.The special strain path was the key to the formation of the unique four-peak texture.The{10–12}twinning and basal slip were two dominant factors to the evolution of texture during MDIF process.Grain strengthening and dislocation strengthening were two main strengthening mechanisms of the forged piece.Besides,the symmetry of yield strength was greatly improved by MDIF process.

Mitigating growth-stress tradeoffs via elevated TOR signaling in rice

Rice production accounts for approximately half of the freshwater resources utilized in agriculture,result-ing in greenhouse gas emissions such as methane(CH4)from flooded paddy fields.To address this chal-lenge,environmentally friendly and cost-effective water-saving techniques have become widely adopted in rice cultivation.However,the implementation of water-saving treatments(WsTs)in paddy-field rice has been associated with a substantial yield loss of up to 50%as well as a reduction in nitrogen use efficiency(NUE).In this study,we discovered that the target of rapamycin(TOR)signaling pathway is compromised in rice under WsT.Polysome profiling-coupled transcriptome sequencing(polysome-seq)analysis unveiled a substantial reduction in global translation in response to WST associated with the downregulation of TOR activity.Molecular,biochemical,and genetic analyses revealed new insights into the impact of the positive TOR-S6K-RPS6 and negative TOR-MAF1 modules on translation repression under WST.Intriguingly,ammonium exhibited a greater ability to alleviate growth constraints under WsT by enhancing TOR signaling,which simultaneously promoted uptake and utilization of ammonium and nitrogen allocation.We further demonstrated that TOR modulates the ammonium transporter AMT1;1 as well as the amino acid permease APP1 and dipeptide transporter NPF7.3 at the translational level through the 5'untranslated region.Collectively,these findings reveal that enhancing TOR signaling could mitigate rice yield penalty due to WST by regulating the processes involved in protein synthesis and NUE.Our study will contribute to the breeding of new rice varieties with increased water and fertilizer utilization efficiency.

Weakened anisotropy of mechanical properties in rolled ZK60 magnesium alloy sheets with elevated deformation temperature

The rolling direction（RD） and the transverse direction（TD） samples were obtained from an as-rolled ZK60 magnesium alloy sheet with strong anisotropy of initial texture and their mechanical properties were tested at various deformation temperatures. Meanwhile, the microstructure and texture of these samples after fracture were investigated. Results revealed that a higher flow stress along the RD than that along the TD at room temperature were ascribed to the strong anisotropy of transitional texture, and this texture effect was remarkably weakened with the increase of deformation temperature. Deformation structure was dominant at 100℃, and was replaced by dynamic recrystallization structure when the deformation temperature increased to 200℃ and 300℃. The texture presented a strong texture（transitional texture in the RD sample and basal texture in the TD sample） at 100℃, but its intensity visibly decreased and texture components became more disperse at 200℃ and 300℃. These microstructure and texture results were employed in conjunction with calculated results to argue that raising deformation temperature could increase the activity of non-basal slip by tailoring the relative critical resolved shear stress of each deformation mode and finally result in low texture effect on mechanical anisotropy.