In this study,four groups of thin plate samples with a wall thickness of 2.2mm,2.5mm,2.7mm,and 3.0mm are prepared by ultra-high vacuum die casting.The effects of Mn,Mg,and Mn/Mg ratio on the microstructure and mechani...In this study,four groups of thin plate samples with a wall thickness of 2.2mm,2.5mm,2.7mm,and 3.0mm are prepared by ultra-high vacuum die casting.The effects of Mn,Mg,and Mn/Mg ratio on the microstructure and mechanical properties of samples with different wall thicknesses are obtained by different test and analysis methods.The results show that as the content of Mn is 0.4%~0.65%,the content of Mg is 0.17%~0.5%,and the Mn/Mg ratio reaches 1.69~1.90,the tensile strength,yield strength,and elongation of HL-111 alloy with a wall thickness of 2~3mm can reach more than 280MPa,120MPa and 10%respectively,and the mechanical properties of the material are greatly improved.In addition,the tensile strength,yield strength,and elongation of HL-111 alloy after T5 heat treatment at 165℃for 510min reach 302.36 MPa,190.32 MPa,and 8.42%.The precipitated phase of Mg2Si leads to changes in strength and elongation.展开更多
Die casting process is widely applied in making Al parts. However, due to high speed of liquid metal flow in the die cavity, gases are prone to be entrapped in the filling, resulting in porosity defects. The X-ray com...Die casting process is widely applied in making Al parts. However, due to high speed of liquid metal flow in the die cavity, gases are prone to be entrapped in the filling, resulting in porosity defects. The X-ray computed tomography scanning technique was used to detect the pores in die-cast ADC12 alloys with different intensification pressures. The three-dimensional features of pores including pore size, number, sphericity have been obtained. The effect of different intensification pressures on two different kinds of pores, namely gas-pores and shrinkage pores, was analyzed. The results show that with increasing the pressure, the pore fractions and quantity gradually decrease. When the pressure increased to 85 MPa, the pores from gas entrapment during the mold filling were compressed, leading to a lower porosity fraction. The pressure cannot affect the pores in the samples with a thin wall (2 mm) due to a great solidification rate.展开更多
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
文摘In this study,four groups of thin plate samples with a wall thickness of 2.2mm,2.5mm,2.7mm,and 3.0mm are prepared by ultra-high vacuum die casting.The effects of Mn,Mg,and Mn/Mg ratio on the microstructure and mechanical properties of samples with different wall thicknesses are obtained by different test and analysis methods.The results show that as the content of Mn is 0.4%~0.65%,the content of Mg is 0.17%~0.5%,and the Mn/Mg ratio reaches 1.69~1.90,the tensile strength,yield strength,and elongation of HL-111 alloy with a wall thickness of 2~3mm can reach more than 280MPa,120MPa and 10%respectively,and the mechanical properties of the material are greatly improved.In addition,the tensile strength,yield strength,and elongation of HL-111 alloy after T5 heat treatment at 165℃for 510min reach 302.36 MPa,190.32 MPa,and 8.42%.The precipitated phase of Mg2Si leads to changes in strength and elongation.
基金financially supported by the Industry Base Enhanced Project(TC160A310-10-01),China
文摘Die casting process is widely applied in making Al parts. However, due to high speed of liquid metal flow in the die cavity, gases are prone to be entrapped in the filling, resulting in porosity defects. The X-ray computed tomography scanning technique was used to detect the pores in die-cast ADC12 alloys with different intensification pressures. The three-dimensional features of pores including pore size, number, sphericity have been obtained. The effect of different intensification pressures on two different kinds of pores, namely gas-pores and shrinkage pores, was analyzed. The results show that with increasing the pressure, the pore fractions and quantity gradually decrease. When the pressure increased to 85 MPa, the pores from gas entrapment during the mold filling were compressed, leading to a lower porosity fraction. The pressure cannot affect the pores in the samples with a thin wall (2 mm) due to a great solidification rate.
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.
