This review presents an in-depth mechanistic analysis of the microstructural refinement and strengthening pathways in Mg-Al alloys,with a focus on the influence of Mg17Al12 precipitates.The Hall-Petch relationsh...This review presents an in-depth mechanistic analysis of the microstructural refinement and strengthening pathways in Mg-Al alloys,with a focus on the influence of Mg17Al12 precipitates.The Hall-Petch relationship,with a slope exceeding 150 MPa·μm1/2 in most AZ-series Mg alloys,underscores the pivotal role of grain size in dictating yield strength.This high sensitivity to grain size is particularly affected by Al content and crystallographic texture of Mg alloys.This necessitates sophisticated thermomechanical treatments such as severe plastic deformation,twin-induced recrystallization,and rapid solidification for effective grain refinement.The Mg17Al12 phase,characterized by its discontinuous or interconnected morphology in as-cast alloys(e.g.,AZ80,AZ91),exerts a strong influence on ductility and fracture resistance.Controlled heat treatments enable modulation of Mg17Al12 morphology,volume fraction,and crystallographic orientation,transitioning from coarse,brittle eutectics to fine,dispersed precipitates with semi-coherent interfaces.These changes fundamentally alter stress accommodation and interaction with dislocations,impacting both precipitation hardening and grain boundary strengthening.However,limited age hardening arises from sluggish solute diffusion and modest precipitation strengthening in the Mg matrix,imposing constraints on high-temperature performance.The review critically evaluates orientation relationships between Mg17Al12 and theα-Mg matrix,detailing their effect on interfacial energies,nucleation sites,and deformation mechanisms.Recent advances in microalloying,process design,and hierarchical microstructure control are discussed to optimize the strength-ductility synergy for automotive applications.Proposed strategies integrate advanced grain refinement,targeted precipitate engineering,and alignment of Mg17Al12 precipitates to achieve application-specific mechanical performance in Mg-Al alloys.展开更多
A combination of rare earth(RE)alloying and plastic deformation was employed to improve the comprehensive properties of Mg-3Al-1Sn-0.5Ca-0.2Mn(ATXM)alloys.The results show that the rolled ATXM-0.1RE alloys exhibit rem...A combination of rare earth(RE)alloying and plastic deformation was employed to improve the comprehensive properties of Mg-3Al-1Sn-0.5Ca-0.2Mn(ATXM)alloys.The results show that the rolled ATXM-0.1RE alloys exhibit remarkable simultaneous improvements in both mechanical strength and corrosion resistance.Specifically,the alloys with Sm,Ce,and Y additions demonstrate yield strengths of 238,232,and 238 MPa,elongations of 18%,17%,and 23%,and corrosion rates of approximately 3.4,2.9,and 1.7 mm/a,respectively.Notably,the rolled ATXM-0.1Y alloy displays the optimal overall properties.The underlying mechanisms involve grain refinement(from~50μm to below 5μm)and alterations in composition,dimension,and arrangement of secondary phases,which contribute to fine-grain strengthening and Orowan strengthening,thereby bolstering mechanical properties.Furthermore,these modifications mitigate the galvanic corrosion and strengthen the protective corrosion product film,resulting in a significantly improved corrosion resistance.展开更多
With the aim to effectively depolymerize polyethylene terephthalate(PET)under mild reaction conditions,PET methanolysis and dimethyl terephthalate(DMT)hydrolysis are integrated in a catalyst system.Firstly,methanolysi...With the aim to effectively depolymerize polyethylene terephthalate(PET)under mild reaction conditions,PET methanolysis and dimethyl terephthalate(DMT)hydrolysis are integrated in a catalyst system.Firstly,methanolysis of PET to DMT is achieved over Cu-Mg-Al oxide catalyst.Next,terephthalic acid(TPA)is prepared by DMT hydrolysis.It is found that hydrolysis of DMT to TPA can be promoted by introducing trace amount of water in this catalyst system.CuO-MgO-4.5Al_2O3catalyst demonstrates the excellent catalytic performance for the depolymerization of PET with high conversion rate and TPA yield(100%and 99.5%,respectively)after reaction at 160℃for 6 h,which provides a new idea for the depolymerization of PET.展开更多
The structural stability, electronic structures, elastic properties and thermodynamic properties of the main binary phases Mg_(17)Al_(12), Al_2Ca, Mg_2 Sn and Mg_2 Ca in Mg-Al-Ca-Sn alloy were determined from the ...The structural stability, electronic structures, elastic properties and thermodynamic properties of the main binary phases Mg_(17)Al_(12), Al_2Ca, Mg_2 Sn and Mg_2 Ca in Mg-Al-Ca-Sn alloy were determined from the first-principles calculation. The calculated lattice parameters are in good agreement with the experimental and literature values. The calculated heats of formation and cohesive energies show that Al_2Ca has the strongest alloying ability and structural stability. The densities of states(DOS), Mulliken electron occupation number, metallicity and charge density difference of these compounds are given. The elastic constants of Mg_(17)Al_(12), Al_2Ca, Mg_2 Sn and Mg_2 Ca phases are calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio are derived. The calculations of thermodynamic properties show that the Gibbs free energies of Al_2Ca and Mg_2 Sn are lower than that of Mg_(17)Al_(12), which indicates that Al_2Ca and Mg_2 Sn are more stable than Mg_(17)Al_(12) phase. Hence, the heat resistance of Mg-Al-based alloys can be improved by adding Ca and Sn additions.展开更多
摘要This review presents an in-depth mechanistic analysis of the microstructural refinement and strengthening pathways in Mg-Al alloys,with a focus on the influence of Mg17Al12 precipitates.The Hall-Petch relationship,with a slope exceeding 150 MPa·μm1/2 in most AZ-series Mg alloys,underscores the pivotal role of grain size in dictating yield strength.This high sensitivity to grain size is particularly affected by Al content and crystallographic texture of Mg alloys.This necessitates sophisticated thermomechanical treatments such as severe plastic deformation,twin-induced recrystallization,and rapid solidification for effective grain refinement.The Mg17Al12 phase,characterized by its discontinuous or interconnected morphology in as-cast alloys(e.g.,AZ80,AZ91),exerts a strong influence on ductility and fracture resistance.Controlled heat treatments enable modulation of Mg17Al12 morphology,volume fraction,and crystallographic orientation,transitioning from coarse,brittle eutectics to fine,dispersed precipitates with semi-coherent interfaces.These changes fundamentally alter stress accommodation and interaction with dislocations,impacting both precipitation hardening and grain boundary strengthening.However,limited age hardening arises from sluggish solute diffusion and modest precipitation strengthening in the Mg matrix,imposing constraints on high-temperature performance.The review critically evaluates orientation relationships between Mg17Al12 and theα-Mg matrix,detailing their effect on interfacial energies,nucleation sites,and deformation mechanisms.Recent advances in microalloying,process design,and hierarchical microstructure control are discussed to optimize the strength-ductility synergy for automotive applications.Proposed strategies integrate advanced grain refinement,targeted precipitate engineering,and alignment of Mg17Al12 precipitates to achieve application-specific mechanical performance in Mg-Al alloys.
基金primarily supported by the National Natural Science Foundation of China(Nos.52234009,52274383,52204389)Partial financial support came from the Scientific Research Innovation Capability Support Project for Young Faculty,China(No.SRICSPYF-ZY2025063).
摘要A combination of rare earth(RE)alloying and plastic deformation was employed to improve the comprehensive properties of Mg-3Al-1Sn-0.5Ca-0.2Mn(ATXM)alloys.The results show that the rolled ATXM-0.1RE alloys exhibit remarkable simultaneous improvements in both mechanical strength and corrosion resistance.Specifically,the alloys with Sm,Ce,and Y additions demonstrate yield strengths of 238,232,and 238 MPa,elongations of 18%,17%,and 23%,and corrosion rates of approximately 3.4,2.9,and 1.7 mm/a,respectively.Notably,the rolled ATXM-0.1Y alloy displays the optimal overall properties.The underlying mechanisms involve grain refinement(from~50μm to below 5μm)and alterations in composition,dimension,and arrangement of secondary phases,which contribute to fine-grain strengthening and Orowan strengthening,thereby bolstering mechanical properties.Furthermore,these modifications mitigate the galvanic corrosion and strengthen the protective corrosion product film,resulting in a significantly improved corrosion resistance.
摘要With the aim to effectively depolymerize polyethylene terephthalate(PET)under mild reaction conditions,PET methanolysis and dimethyl terephthalate(DMT)hydrolysis are integrated in a catalyst system.Firstly,methanolysis of PET to DMT is achieved over Cu-Mg-Al oxide catalyst.Next,terephthalic acid(TPA)is prepared by DMT hydrolysis.It is found that hydrolysis of DMT to TPA can be promoted by introducing trace amount of water in this catalyst system.CuO-MgO-4.5Al_2O3catalyst demonstrates the excellent catalytic performance for the depolymerization of PET with high conversion rate and TPA yield(100%and 99.5%,respectively)after reaction at 160℃for 6 h,which provides a new idea for the depolymerization of PET.
基金Project(20131083) supported by the Doctoral Starting up Foundation of Liaoning Province,ClhinaProject(LT201304) supported by the Program for Liaoning Innovative Research Team in University,ChinaProject(2013201018) supported by the Key Technologies Research and Development Program of Liaoning Province,China
摘要The structural stability, electronic structures, elastic properties and thermodynamic properties of the main binary phases Mg_(17)Al_(12), Al_2Ca, Mg_2 Sn and Mg_2 Ca in Mg-Al-Ca-Sn alloy were determined from the first-principles calculation. The calculated lattice parameters are in good agreement with the experimental and literature values. The calculated heats of formation and cohesive energies show that Al_2Ca has the strongest alloying ability and structural stability. The densities of states(DOS), Mulliken electron occupation number, metallicity and charge density difference of these compounds are given. The elastic constants of Mg_(17)Al_(12), Al_2Ca, Mg_2 Sn and Mg_2 Ca phases are calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio are derived. The calculations of thermodynamic properties show that the Gibbs free energies of Al_2Ca and Mg_2 Sn are lower than that of Mg_(17)Al_(12), which indicates that Al_2Ca and Mg_2 Sn are more stable than Mg_(17)Al_(12) phase. Hence, the heat resistance of Mg-Al-based alloys can be improved by adding Ca and Sn additions.