The solidification microstructure and mechanical properties of hypoeutectic Al-10Mg_(2)Si cast alloys with different Cu contents and 0.45 wt.% Er were investigated using an optical microscope, scanning electron micros...The solidification microstructure and mechanical properties of hypoeutectic Al-10Mg_(2)Si cast alloys with different Cu contents and 0.45 wt.% Er were investigated using an optical microscope, scanning electron microscope, and an electronic universal testing machine. Results showed that Cu and Er could significantly reduce the grain size of the eutectic Mg;Si phase from 15.4 μm for the base alloy to 5.8 μm for the alloy with 1.5 wt.% Cu and 0.45 wt.% Er.Meanwhile, the needle-like β-Al5Fe Si phase was modified to fine sized irregular shaped Cu, Er and Fe-rich particles with the additions of Cu and Er. The strength and ductility of the Al-10Mg_(2)Si as-cast alloys were simultaneously improved by the additions of Cu and Er, and the ultimate tensile strength, yield strength and elongation increase from 223 MPa,136 MPa and 2.1% to 337 MPa, 169 MPa and 4.7%, respectively. The heterogeneous nucleation of Mg_(2)Si on Al P was avoided by forming Cu, Er and P-containing phases, due to the additions of Cu and Er. Moreover, the Cu and Er atomic clusters and their intermetallic segregated on the surface of the eutectic Mg_(2)Si and inhibited the growth of the eutectic Mg_(2)Si, which were responsible for the modification of the eutectic Mg_(2)Si.展开更多
本文采用第一性原理对纯Al2O3和Si掺杂的Si0.167Al0.833O1.5,Si0.25Al0.75O1.5晶体体系的能带结构、态密度进行了计算分析.结果发现:随着Si在Al2O3晶体中所占比例的增加,体系能隙变小,在Si0.25Al0.75O1.5晶体体系中能隙已降到2.5 e V,...本文采用第一性原理对纯Al2O3和Si掺杂的Si0.167Al0.833O1.5,Si0.25Al0.75O1.5晶体体系的能带结构、态密度进行了计算分析.结果发现:随着Si在Al2O3晶体中所占比例的增加,体系能隙变小,在Si0.25Al0.75O1.5晶体体系中能隙已降到2.5 e V,表明该体系为半导体材料;而在掺杂的体系中有数条分散的能带穿过了费米能级,即可以预测该掺杂体系有特别的光电性质;同时对比纯Al2O3和Si掺杂的Si0.167Al0.833O1.5,Si0.25Al0.75O1.5晶体体系的总态密度,发现掺杂体系的价带和导带向低能区域移动.展开更多
基金Project(51971106) supported by the National Natural Science Foundation of ChinaProject(GJJ191094) supported by the Education Department of Jiangxi Province,China+2 种基金Project(PA2019GDZC0096) supported by Fundamental Research Funds for the Central Universities of ChinaProject(2019-MS-171) supported by the Liaoning Natural Science Foundation,ChinaProject supported by Programs for Liaoning Innovative Talents/Groups and Liaoning Distinguished Professors,China。
文摘The solidification microstructure and mechanical properties of hypoeutectic Al-10Mg_(2)Si cast alloys with different Cu contents and 0.45 wt.% Er were investigated using an optical microscope, scanning electron microscope, and an electronic universal testing machine. Results showed that Cu and Er could significantly reduce the grain size of the eutectic Mg;Si phase from 15.4 μm for the base alloy to 5.8 μm for the alloy with 1.5 wt.% Cu and 0.45 wt.% Er.Meanwhile, the needle-like β-Al5Fe Si phase was modified to fine sized irregular shaped Cu, Er and Fe-rich particles with the additions of Cu and Er. The strength and ductility of the Al-10Mg_(2)Si as-cast alloys were simultaneously improved by the additions of Cu and Er, and the ultimate tensile strength, yield strength and elongation increase from 223 MPa,136 MPa and 2.1% to 337 MPa, 169 MPa and 4.7%, respectively. The heterogeneous nucleation of Mg_(2)Si on Al P was avoided by forming Cu, Er and P-containing phases, due to the additions of Cu and Er. Moreover, the Cu and Er atomic clusters and their intermetallic segregated on the surface of the eutectic Mg_(2)Si and inhibited the growth of the eutectic Mg_(2)Si, which were responsible for the modification of the eutectic Mg_(2)Si.
文摘本文采用第一性原理对纯Al2O3和Si掺杂的Si0.167Al0.833O1.5,Si0.25Al0.75O1.5晶体体系的能带结构、态密度进行了计算分析.结果发现:随着Si在Al2O3晶体中所占比例的增加,体系能隙变小,在Si0.25Al0.75O1.5晶体体系中能隙已降到2.5 e V,表明该体系为半导体材料;而在掺杂的体系中有数条分散的能带穿过了费米能级,即可以预测该掺杂体系有特别的光电性质;同时对比纯Al2O3和Si掺杂的Si0.167Al0.833O1.5,Si0.25Al0.75O1.5晶体体系的总态密度,发现掺杂体系的价带和导带向低能区域移动.
