The effects of Si content on the microstructure and yield strength of Al-(1.44-12.40)Si-0.7 Mg(wt.%)alloy sheets under the T4 condition were systematically studied via laser scanning confocal microscopy(LSCM),DSC,TEM ...The effects of Si content on the microstructure and yield strength of Al-(1.44-12.40)Si-0.7 Mg(wt.%)alloy sheets under the T4 condition were systematically studied via laser scanning confocal microscopy(LSCM),DSC,TEM and tensile tests.The results show that the recrystallization grain of the alloy sheets becomes more refined with an increase in Si content.When the Si content increases from 1.44 to 12.4 wt.%,the grain size of the alloy sheets decreases from approximately 47 to 10μm.Further,with an increase in Si content,the volume fraction of the GP zones in the matrix increases slightly.Based on the existing model,a yield strength model for alloy sheets was proposed.The predicted results are in good agreement with the actual experimental results and reveal the strengthening mechanisms of the Al-(1.44-12.40)Si-0.7 Mg alloy sheets under the T4 condition and how they are influenced by the Si content.展开更多
The actual effective partition coefficients of Mg and Cr in a cross-section of a dendrite arm in a direct-chill(DC)-casting ingot of 7475 aluminum alloy are obtained.Meanwhile,by analyzing the microstructure,the mecha...The actual effective partition coefficients of Mg and Cr in a cross-section of a dendrite arm in a direct-chill(DC)-casting ingot of 7475 aluminum alloy are obtained.Meanwhile,by analyzing the microstructure,the mechanism of the heterogeneous distribution of E(Al_(18)Mg_(3)Cr_(2))dispersoids in this DC ingot is revealed.The results show that the actual effective partition coefficients of Mg and Cr are 0.650 and 1.392,respectively,and they describe the heterogeneous distributions of Mg and Cr along the direction of radius of the cross-section of the dendrite arm of the alloy.After homogenization treatment at 470℃ for 24 h,Mg diffuses uniformly,but Cr hardly diffuses.Both the concentrations of Mg and Cr and the sites of heterogeneous nucleation in the alloy are the determinants of the formation of E dispersoids simultaneously.The heat treatment at 250℃ for 72 h provides a large number of the sites of heterogeneous nucleation of the formation of fine E dispersoids that will be formed in the center of the cross-section during the subsequent heat treatment at higher temperature.展开更多
基金Project(2016YFB0300801)supported by the National Key Research and Development Program of ChinaProject(51871043)supported by the National Natural Science Foundation of ChinaProject(N180212010)supported by the Fundamental Research Funds for the Central Universities of China。
文摘The effects of Si content on the microstructure and yield strength of Al-(1.44-12.40)Si-0.7 Mg(wt.%)alloy sheets under the T4 condition were systematically studied via laser scanning confocal microscopy(LSCM),DSC,TEM and tensile tests.The results show that the recrystallization grain of the alloy sheets becomes more refined with an increase in Si content.When the Si content increases from 1.44 to 12.4 wt.%,the grain size of the alloy sheets decreases from approximately 47 to 10μm.Further,with an increase in Si content,the volume fraction of the GP zones in the matrix increases slightly.Based on the existing model,a yield strength model for alloy sheets was proposed.The predicted results are in good agreement with the actual experimental results and reveal the strengthening mechanisms of the Al-(1.44-12.40)Si-0.7 Mg alloy sheets under the T4 condition and how they are influenced by the Si content.
基金financially supported by the National Natural Science Foundation of China(No.51871043)Fundamental Research Funds for the Central Universities of China(No.N180212010)Liaoning Natural Science Foundation of China(No.2019-MS-113)。
文摘The actual effective partition coefficients of Mg and Cr in a cross-section of a dendrite arm in a direct-chill(DC)-casting ingot of 7475 aluminum alloy are obtained.Meanwhile,by analyzing the microstructure,the mechanism of the heterogeneous distribution of E(Al_(18)Mg_(3)Cr_(2))dispersoids in this DC ingot is revealed.The results show that the actual effective partition coefficients of Mg and Cr are 0.650 and 1.392,respectively,and they describe the heterogeneous distributions of Mg and Cr along the direction of radius of the cross-section of the dendrite arm of the alloy.After homogenization treatment at 470℃ for 24 h,Mg diffuses uniformly,but Cr hardly diffuses.Both the concentrations of Mg and Cr and the sites of heterogeneous nucleation in the alloy are the determinants of the formation of E dispersoids simultaneously.The heat treatment at 250℃ for 72 h provides a large number of the sites of heterogeneous nucleation of the formation of fine E dispersoids that will be formed in the center of the cross-section during the subsequent heat treatment at higher temperature.
