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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。
Pure aluminum and Al-1% Sc alloy as raw material, obtained by smelting Sc microalloyed pure aluminum (Al-0.1% Sc). X-ray diffraction (XRD) analysis, electron backscatter diffraction (EBSD) analysis and tensile tests were carried out to investigate the microstructure evolution of Al-0.1% Sc alloy during ECAP and large strain deformation And strengthen the mechanism. ECAP test using the process of Bc 3 times the extrusion process, that is, after each extrusion along the axial direction of the workpiece rotated 90 °, the same direction of rotation, the extrusion speed of 5 mm · s-1. The results show that the average grain size decreases and the grain size is reduced to less than 4 mm by ECAP. The strength of the alloy is significantly increased from 105 MPa to 162 MPa and the low angle crystal Which decreased from 0.889 to 0.652. A certain amount of dislocations were accumulated in the alloy, and the dislocation density was 0.5321014 m-2. However, the subsequent compressive strain treatment has little effect on the average grain size of the alloy, which increases the tensile strength of the alloy to 176 MPa, increases the low-angle grain boundary ratio of the alloy to 0.765, and increases the dislocation density of the alloy to 1.7151014 m-2. The strengthening of the large strain Al-0.1% Sc alloy is mainly composed of lattice friction stress, dislocation strengthening, low-angle grain boundary strengthening and high-angle grain boundary strengthening, among which the strengthening contribution of low-angle grain boundaries and dislocation accounts for the vast majority.