The evolution of microstructure and mechanical properties of Al-0.4 Cu-0.14 Si-0.05 Mg-0.2 Fe（wt.%）alloys, micro-alloyed with Zr, Ti and Sc, were investigated. The addition of 0.2%Zr to base alloy accelerates the pr...The evolution of microstructure and mechanical properties of Al-0.4 Cu-0.14 Si-0.05 Mg-0.2 Fe（wt.%）alloys, micro-alloyed with Zr, Ti and Sc, were investigated. The addition of 0.2%Zr to base alloy accelerates the precipitation of Si-rich nano-phase in α-Al matrix, which plays an important role in improving the mechanical properties of an alloy. The tensile strength increases from 102 MPa for the base alloy to 113 MPa for the Zr-modified alloy. Adding 0.2%Zr + 0.2%Ti to base alloy effectively refines a-Al grain size and accelerates the precipitation of Si and Cu elements, leading to heavy segregation at grain boundary.By further adding 0.2%Sc to Zr + Ti modified alloy, the segregation of Si and Cu elements is suppressed and more Si and Cu precipitates appeared in α-Al matrix. Accompanied with the formation of coherent Al;Sc phase, the tensile strength increases from 108 MPa for the Zr + Ti modified alloy to 152 MPa for the Sc-modified alloy. Due to excellent thermal stability of Al;Sc phase, the Sc-modified alloy exhibits obvious precipitation hardening behavior at 350℃, and the tensile strength increases to 203 MPa after holding at 350 ℃ for 200 h.展开更多
Element Sc is a promising candidate for optimizing the high-temperature mechanical properties of Al alloys.In this study,the Sc-solute,Al_(3) Sc-vacancy and Al_(3) Sc-solute interactions in aluminium are inves-tigated...Element Sc is a promising candidate for optimizing the high-temperature mechanical properties of Al alloys.In this study,the Sc-solute,Al_(3) Sc-vacancy and Al_(3) Sc-solute interactions in aluminium are inves-tigated extensively by using first-principles calculations.The correlation between the various interaction energies and the solute atomic size,and the Sc-solute compound formation energy has been evaluated.A negative correlation between the first nearest neighbour Sc-solute binding energies and the lowest Sc-solute compound formation energies has been identified,while the second nearest neighbour Sc-solute binding energies increase monotonically with the solute atomic size.Al_(3) Sc precipitates can bind vacancy strongly at the specific atomic site,but their relatively low number density limits their influence on va-cancy behaviours during the ageing period shortly after quenching.Compared to the atomic size,the trend for solute segregating at the interface between Al_(3) Sc precipitate and Al bulk is more strongly re-lated to the Sc-solute binding energy.The calculated results can clarify the available experimental obser-vations for Al-Sc,Al-Cu,Al-Mg-Si and Al-Zn-Mg-Cu alloys,and it is hoped to guide the design of high-performance Al alloys.展开更多
The static recrystallization behavior of 7075 aluminum alloy containing Al_(3)(Sc,Zr)phase prepared by casting and the relationship between recrystallization behavior and mechanical properties were studied.The additio...The static recrystallization behavior of 7075 aluminum alloy containing Al_(3)(Sc,Zr)phase prepared by casting and the relationship between recrystallization behavior and mechanical properties were studied.The addition of Sc and Zr made the Sc−Zr−7075 aluminum alloy remain the most of fibrous structure and high-density dislocations formed in the extrusion process,resulting in the recrystallization fraction of the alloy decreasing from 35%to 22%,and the corresponding fraction of substructure increasing from 59%to 67%.The Sc and Zr effectively inhibited the recrystallization behavior of 7075 aluminum alloy mainly,which was attributed to the fact that the existence of fine and coherent Al_(3)(Sc,Zr)phase(r=35 nm,f=1.8×10^(−3))strongly pined the dislocations and grain boundaries,preventing the dislocations from rearranging into sub-grain boundaries and from developing into high angle grain boundaries,and further hindering the formation and growth of recrystallized core of the alloy.展开更多
基金financial support of the project from the National Key Research and Development Project of China(No.2016YFB0301001,TC160A310-10)the Opening Fund of State Key Laboratory of Metal Matrix Composite(No.mmckdf16-03)Shanghai Jiao Tong University startup funding(No.13X100040023)
文摘The evolution of microstructure and mechanical properties of Al-0.4 Cu-0.14 Si-0.05 Mg-0.2 Fe（wt.%）alloys, micro-alloyed with Zr, Ti and Sc, were investigated. The addition of 0.2%Zr to base alloy accelerates the precipitation of Si-rich nano-phase in α-Al matrix, which plays an important role in improving the mechanical properties of an alloy. The tensile strength increases from 102 MPa for the base alloy to 113 MPa for the Zr-modified alloy. Adding 0.2%Zr + 0.2%Ti to base alloy effectively refines a-Al grain size and accelerates the precipitation of Si and Cu elements, leading to heavy segregation at grain boundary.By further adding 0.2%Sc to Zr + Ti modified alloy, the segregation of Si and Cu elements is suppressed and more Si and Cu precipitates appeared in α-Al matrix. Accompanied with the formation of coherent Al;Sc phase, the tensile strength increases from 108 MPa for the Zr + Ti modified alloy to 152 MPa for the Sc-modified alloy. Due to excellent thermal stability of Al;Sc phase, the Sc-modified alloy exhibits obvious precipitation hardening behavior at 350℃, and the tensile strength increases to 203 MPa after holding at 350 ℃ for 200 h.
基金financially supported by the National Natural Science Foundation of China(Nos.52071284 and 51771172)the Zhejiang Provincial Natural Science Foundation of China(No.LQ22E010003).
文摘Element Sc is a promising candidate for optimizing the high-temperature mechanical properties of Al alloys.In this study,the Sc-solute,Al_(3) Sc-vacancy and Al_(3) Sc-solute interactions in aluminium are inves-tigated extensively by using first-principles calculations.The correlation between the various interaction energies and the solute atomic size,and the Sc-solute compound formation energy has been evaluated.A negative correlation between the first nearest neighbour Sc-solute binding energies and the lowest Sc-solute compound formation energies has been identified,while the second nearest neighbour Sc-solute binding energies increase monotonically with the solute atomic size.Al_(3) Sc precipitates can bind vacancy strongly at the specific atomic site,but their relatively low number density limits their influence on va-cancy behaviours during the ageing period shortly after quenching.Compared to the atomic size,the trend for solute segregating at the interface between Al_(3) Sc precipitate and Al bulk is more strongly re-lated to the Sc-solute binding energy.The calculated results can clarify the available experimental obser-vations for Al-Sc,Al-Cu,Al-Mg-Si and Al-Zn-Mg-Cu alloys,and it is hoped to guide the design of high-performance Al alloys.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51871111)the Natural Science Foundation of Shandong Province,China(No.ZR2018LE001)+1 种基金the Science and Technology Program of University of Ji’nan,China(Nos.XKY2036,XKY1713)the Key Research and Development Program of Shandong Province,China(No.2019GGX102008).
文摘The static recrystallization behavior of 7075 aluminum alloy containing Al_(3)(Sc,Zr)phase prepared by casting and the relationship between recrystallization behavior and mechanical properties were studied.The addition of Sc and Zr made the Sc−Zr−7075 aluminum alloy remain the most of fibrous structure and high-density dislocations formed in the extrusion process,resulting in the recrystallization fraction of the alloy decreasing from 35%to 22%,and the corresponding fraction of substructure increasing from 59%to 67%.The Sc and Zr effectively inhibited the recrystallization behavior of 7075 aluminum alloy mainly,which was attributed to the fact that the existence of fine and coherent Al_(3)(Sc,Zr)phase(r=35 nm,f=1.8×10^(−3))strongly pined the dislocations and grain boundaries,preventing the dislocations from rearranging into sub-grain boundaries and from developing into high angle grain boundaries,and further hindering the formation and growth of recrystallized core of the alloy.
