Sun Fengshan, Wen Xin, Sun Shuaifei, Lu Yuanyuan, Xiao Wenlong, Ma Chaoli
School of Materials Science and Engineering, Beihang University, Beijing 100191, China.
Tianmushan Laboratory, Hangzhou 310023, China.
Materials (Basel). 2024 Jul 22;17(14):3607. doi: 10.3390/ma17143607.
The effects of chromium (Cr) addition ranging 0.1-0.3 wt.% on the microstructure and mechanical properties of Al-7Si-4Cu-0.25Mg (wt.%) alloy have been investigated. The cast Cr-free alloy consisted of α-Al, eutectic Si, Q-AlMgCuSi and θ-AlCu phases. Doping of Cr resulted in the appearance of a polyhedron-shaped α-AlCrSi phase with a cubic structure. The AlCrSi particles were found to embed with AlCu blocks and bring about size reduction for the AlCu blocks. The area fraction of AlCrSi monotonously increased with Cr content. After T6 treatment, the AlCu blocks almost fully dissolved and transformed to θ'-AlCu precipitates in the Cr-containing alloys. TEM observation revealed relatively large-sized θ' precipitates attached to AlCrSi dispersoids. The Cr-containing alloys showed impressive mechanical properties, with the peak strength up to 452 MPa at room temperature. The ductility exhibited an increasing trend with Cr content, but the strength dropped dramatically when the Cr content reached 0.3 wt.%. It is suggested that the strength contribution from the AlCrSi phase is limited, especially at an elevated temperature.
研究了添加0.1-0.3 wt.%铬（Cr）对Al-7Si-4Cu-0.25Mg（wt.%）合金微观结构和力学性能的影响。铸态无铬合金由α-Al、共晶硅、Q-AlMgCuSi和θ-AlCu相组成。Cr的掺杂导致出现具有立方结构的多面体形状的α-AlCrSi相。发现AlCrSi颗粒与AlCu块嵌入在一起，并使AlCu块尺寸减小。AlCrSi的面积分数随Cr含量单调增加。经过T6处理后，AlCu块几乎完全溶解并在含Cr合金中转变为θ'-AlCu析出物。透射电镜观察显示相对较大尺寸的θ'析出物附着在AlCrSi弥散体上。含Cr合金表现出令人印象深刻的力学性能，室温下峰值强度高达452 MPa。延展性随Cr含量呈增加趋势，但当Cr含量达到0.3 wt.%时强度急剧下降。研究表明，AlCrSi相的强度贡献有限，尤其是在高温下。
