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

Abstract:

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 parts of the parts. How to improve the uniformity of the semi-solid structure is the key to obtaining molded parts with excellent comprehensive performance. In this paper, the wall thickness of four kinds of parts are designed, and the influence of the wall thickness of the parts on the microstructure uniformity and performance of rheological extrusion parts is studied. Research indicates: The microstructures of CuSn10P1 alloy semi-solid extrusion castings with different wall thicknesses are all composed of α-Cu phase, δ-Cu41Sn11 phase, β"-Cu13.7Sn phase and Cu3P phase. As the wall thickness decreases, the solid-liquid two-phase synergistic deformation ability of CuSn10P1 alloy semi-solid slurry becomes worse during filling. This resulted in the uneven distribution of the microstructure along the filling direction, and the intergranular structure (α+δ+Cu3P) gradually showed a large-area network or long strip with uneven distribution of clusters. The size of primary α-Cu grains decreases first and then increases, and the primary α-Cu grains of 10mm 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 homogenization of the structure, the solid solution strengthening effect and the fine grain strengthening effect.

Key words:semi-solid, CuSn10P1 alloy, structure;uniformity, performance