壁厚对半固态流变挤压铸造CuSn10P1合金微观组织均匀性和性能的影响

Effect of Wall Thickness on Microstructure Uniformity and Properties of CuSn10P1 Alloy in Semi-solid Rheological Squeeze Casting

显微组织的不均匀性影响零部件的综合性能,而半固态成形的特性易引起零部件不同部位显微组织存在较大差异,如何改善半固态组织均匀性是获得性能优异成形件的关键。本研究设计4种零件壁厚,研究零件壁厚对流变成形件显微组织均匀性及性能的影响。结果表明:不同壁厚CuSn10P1合金半固态挤压铸件的显微组织均由α-Cu相、δ-Cu_(41)Sn_(11)相、β′-Cu_(13.7)Sn相和Cu_(3)P相4种相构成。随着壁厚的减小,CuSn10P1合金半固态浆料充型时固液两相协同变形能力变差,导致了显微组织沿充型方向上的不均匀分布,晶间组织(α+δ+Cu_(3)P)逐渐呈大面积网状或者长条状且团簇聚集分布不均。初生α-Cu晶粒尺寸先减小后增大,其中10 mm壁厚铸件初生α-Cu晶粒最为细小。随着壁厚减小,CuSn10P1合金半固态挤压铸件的室温抗拉强度和延伸率均呈先增加后降低的趋势,当壁厚为10 mm时性能最佳,分别为445.7 MPa和37.78%,这主要归功于其组织均匀化、固溶强化效应和细晶强化效应。

The inhomogeneity of the microstructure affects the comprehensive performance of the parts,and the characteristics of semi-solid forming can easily cause large differences in the microstructures of different regions of the regions.How to improve the uniformity of the semi-solid structure is the key to obtaining molded parts with excellent comprehensive performance.In this research,the wall thickness of four kinds of parts were designed,and the influence of the wall thickness of the parts on the microstructure uniformity and performance of rheological extrusion parts was studied.Results show that the microstructures of CuSn10P1 alloy semi-solid extrusion castings with different wall thicknesses are all composed ofα-Cu phase,δ-Cu_(41)Sn_(11)phase,β'-Cu_(13.7)Sn phase and Cu_(3)P phase.As the wall thickness decreases,the solid-liquid two-phase synergistic deformation ability of CuSn_(10)P1 alloy semi-solid slurry becomes worse during filling.These results in the uneven distribution of the microstructure along the filling direction,and the intergranular structure(α+δ+Cu_(3)P)gradually show a large-area network or long strip with uneven distribution of clusters.The size of primaryα-Cu grains decreases first and then increases,and the primaryα-Cu grains of 10 mm wall thickness castings are the smallest.As the wall thickness decreases,the room temperature tensile strength and elongation of CuSn10P1 alloy semi-solid extrusion castings both increase first and then decrease.When the wall thickness is 10 mm,the performance is the best,445.7 MPa and 37.78%,respectively.This is mainly due to the homog enization of the structure,the solid solution strengthening effect and the fine grain strengthening effect.