中文摘要：

以工业纯铝和Al^-1%Sc合金为原料,通过熔炼得到Sc微合金化纯铝（Al-0.1%Sc）。采用X射线衍射（XRD）分析、电子背散射衍射（EBSD）分析技术以及拉伸实验,研究了Al-0.1%Sc合金在等通道转角挤压（ECAP）和压缩大应变加工过程中的组织演变和强化机制。ECAP试验采用工艺路线Bc进行3道次挤压加工,即每次挤压后将工件沿轴线方向旋转90°,旋转方向不变,挤压速度为5 mm·s^^-1。结果表明：ECAP加工使得合金平均晶粒尺寸减小,晶粒尺寸基本被细化到4 mm以下;显著提高了合金强度,抗拉强度由105 MPa提高到162 MPa;降低了合金中低角度晶界比例,从0.889减小到0.652;使得合金内部积累了一定量的位错,位错密度为0.5321014 m^-2。而后续的压缩大应变加工对合金的平均晶粒尺寸几乎没有影响,使得合金的抗拉强度提高到176 MPa,使得合金的低角度晶界比例提高到0.765,使得合金的位错密度提高到1.7151014 m^-2。大应变Al-0.1%Sc合金的强化主要由晶格摩擦应力、位错强化、低角度晶界强化和高角度晶界强化组成,其中低角度晶界和位错的强化贡献占绝大部分。

英文摘要：

The Sc-microalloyed pure aluminum（Al^-1% Sc） was made from industry pure aluminum and Al^-1% Sc alloy by melting.Microstructure evolution and strengthening mechanisms of Al-0. 1% Sc alloy during equal-channel angular pressing（ECAP） and compressing were researched by X-ray diffraction（XRD）,electron backscattered diffraction（EBSD） analysis and tensile test. In the ECAP test,the process Route Bc was used to carry out the 3 passes extrusion process,and the extrusion speed was 5 mm·s^^-1. In the process Route Bc,the workpiece would be rotated 90° along the axis after each extrusion and the direction of the rotation was constant.The results indicated that the Al-0. 1% Sc alloys processed by ECAP had a reduction on grain size and most grains were refined to4 mm or less,and the tensile strength was improved from 105 to 162 MPa. The proportion of low angle grain boundary of the Al-0. 1%Sc alloys processed by ECAP was lower and it was reduced from 0. 889 to 0. 652. There was a certain amount of dislocation in the Al-0. 1% Sc alloys processed by ECAP and the dislocation density was 0. 5321014 m^-2. The subsequent compressing large strain processing almost had no effect on the average grain size of the alloy. The tensile strength and the proportion of low angle grain boundary after the compressing large strain processing were respectively increased to 176 MPa and 0. 765. And the subsequent compressing large strain processing increased the dislocation density to 1. 7151014 m^-2. Strengthening contributions of large strain Al-0. 1% Sc alloy were mainly from lattice friction stress,dislocation strengthening,low angle grain boundary and high angle grain boundary strengthening.And low angle grain boundary and dislocation strengthening were dominant.