Primary Si refinement and eutectic Si modification in Al-20Si via P-Ce addition

Abstract

Enhancing the mechanical properties of hypereutectic Al-Si alloys by refining the primary and eutectic Si morphology is very challenging. In this study, the refinement mechanism of primary and eutectic Si morphologies via the simultaneous addition of P-Ce into the Al-20Si alloy was studied. Microstructural analysis revealed that the primary and eutectic Si morphologies were significantly refined, which increased the tensile strength. Furthermore, the addition of Ce, up to 0.6 wt%, can result in the formation of Ce-rich intermetallic phases, which may lead to a significantly increased tensile strength while retaining the ductility of the alloy. The ultimate tensile strength of the Al-20Si alloy increased from 96 to 175 MPa, and the elongation increased from 1.0% to 1.7% with the addition of P-Ce. Moreover, the wear resistance of the alloy improved. The added P and Ce did not react with each other to form an intermetallic compound; therefore, this method can simultaneously refine primary and eutectic Si.

Study on mechanism of refining and modifying in Al–Si–Mg casting alloys with adding rare earth cerium

“…Figure 10(c) shows the diffraction spot (SAED) at one point on the gray strip-like phase. After calibration, it is concluded that the gray strip-like phase is the Al 8 Si 6 Mg 3 Fe phase [19,28], and the crystal band axis is [−1210]. Combined with the Mapping results in figures 10(d)-(g), it is found that Al, Si, Mg, and Fe are abundantly enriched in the gray elongated phase, which verifies that the elongated phase is Al 8 Si 6 Mg 3 Fe.…”

“…Adding trace amounts of Y [11], Mn, Mo [12,13], La and Zr [14,15] to hypoeutectic Al-Si alloys can change the morphology of the alloy, reduce the size of eutectic Si, and refine α-Al dendrites. Among the various available rare earth elements, Ce has become a good candidate element for microalloying of Al-Si casting alloys in terms of cost and demand in the metallurgical market [16][17][18][19][20][21]. Cai Yuzhou [22] et al added Ce in the Al-7Si-0.35Mg alloy, two phases of Ce-23Al-22Si and Al-17Ce-12Ti-2Si-2Mg were formed in the alloy, and the eutectic Si was well obtained.…”

Effect of Cooling Rate on Nano-Eutectic Formation in Laser Surface Remelted and Rare Earth Modified Hypereutectic Al-20Si Alloys

“…Rare earth element addition to the Al-Si binary system has long been an area of investigation. Still, the mechanism behind the micro-alloying of rare earth element modifications, namely refinement of Si phases and coupled zone transitions, has not been fully understood [41]. It can be speculated that, since the heat history within the melt pool is similar, the undercooling amounts caused by micro-alloying elements are different.…”