Effects of Sr+Ce on Microstructure and Abrasive Resistance of <i>In-Situ</i> Mg₂Si/Al-Si-Cu Composites

Abstract

In the present study, the modi cation effect of Sr+Ce in Mg 2 Si/Al-Si-Cu composites was investigated for controlling both the microstructure and mechanical properties. Furthermore, the hardness and the abrasive resistance after modi cation were also studied. The results show that when the composites were modi ed by 0.40 mass% Ce, the morphology of the primary Mg 2 Si phase changes to a polygonal morphology with a size of 15 μm. However, in those with a 0.40 mass% Ce and 0.05 mass% Sr addition, the morphology changes to an irregular and equiaxed shape, and the size increases to 50 μm. Furthermore, in the 0.40 mass% Ce and 0.10 mass% Sr addition, the primary Mg 2 Si morphology transforms to a rectangular trapezoid, or T shape, with sizes measuring 70 μm. Additionally, in the 1.00 mass% Ce and 0.05 mass% Sr, and the 1.00 mass% Ce and 0.10 mass% Sr addition, the primary Mg 2 Si morphologies become either polygonal or irregular shaped, respectively. The eutectic phases change shows that, with the addition of Ce or Sr, the eutectic phases exist in the form of the binary eutectic of Al+Mg 2 Si or the ternary eutectic of Al+Mg 2 Si+Si. The hardness test illustrates that the hardness of the 1.00 mass% Ce and 0.05 mass% Sr and the 0.40 mass% Ce and 0.05 mass% Sr, modi ed composites are higher than the unmodi ed composites. The abrasive resistance data shows that modi ed composites with the 1.00 mass% Ce and 0.05 mass% Sr are higher than that of the modi ed and unmodi ed composites with a 0.40 mass% Ce and 0.05 mass% Sr. The abrasive resistance agrees with the hardness test results, and this demonstrates that the Sr+Ce addition can change the microstructure and enhance the mechanical properties of the material.

Study on non-equilibrium solidification microstructure of Al–Cu3–Si–Mg alloy by MMDF

“…These two phases served as non-uniform nucleating particles to increase the nucleation rate and refine the as-cast microstructures. Qin [15] et al studied the effect of the addition of rare earth element Sr/Ce on the in situ Mg 2 Si/Al-Si-Cu composites, which shows that the addition of rare earth elements Ce has a refining effect on the size of both the aluminum alloy matrix and the in situ Mg 2 Si. According to the analysis of the experimental results in this paper, the addition of rare earth element La/Ce and titanium reacted to form polygon intermetallic compounds Al x Ti 9 La 2 Ce 6 Cu at the initial solidification stage.…”

Effect of Si Content of Matrix Alloy on the Microstructure and Properties of Sip/Al-Si-Mg Composites Prepared by Pressure Infiltration Method

“…The main drawbacks of those techniques [5,6] can be referred as weak interfacial bonding and undesirable chemical reaction, which leads to the poor properties (especially the mechanical and thermo-physical properties) of the composites [7,8]. However, pressure infiltration method at high temperature can overcome the above problems [9][10][11].…”