Microstructure Evolution and Performance Improvement of Hypereutectic Al–Mg2Si Metallic Composite with Ca or Sb

Abstract

In this article, the modification effects on Al–Mg2Si before and after heat treatment were investigated with Ca, Sb, and (Ca + Sb). In comparison with single Ca or Sb, the samples with composition modifiers (Ca + Sb) had the optimal microstructure. The sample with a molar ratio for Ca-to-Sb of 1:1 obtained relatively higher properties, for which the Brinell hardness values before and after heat treatment were remarkably increased by 31.74% and 28.93% in comparison with bare alloy. According to differential scanning calorimetry analysis (DSC), it was found that the nucleation behavior of the primary Mg2Si phase could be significantly improved by using chemical modifiers. Some white particles were found to be embedded in the center of Mg2Si phases, which were deduced to be Ca5Sb3 through X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM) analyses. Furthermore, Ca5Sb3 articles possess a rather low mismatch degree with Mg2Si particles based on Phase Transformation Crystallography Lab software (PTCLab) calculation, meaning that the efficient nucleation capability of Ca5Sb3 for Mg2Si particles could be estimated.

Microstructure Control and Performance Evolution of Hypereutectic Al–20Mg2Si Alloy by Novel Al–Ca–Sb Masteralloy

“…According to the previous researches, it was found that the molar ratio of Ca and Sb had a significant influence on the composite modification effect on Al–Mg 2 Si alloys and the optimum molar ratio of Ca and Sb was reported to be 1:1. [ 23 ] In our research, a novel Al–3.3Ca–10Sb masteralloy containing AlCa 11 Sb 9 and CaSb 2 particles was successfully synthesized and its composite modification effect on the microstructure evolution and mechanical properties of Al–Mg 2 Si alloy was analyzed in detail. Furthermore, the composite modification mechanism of this novel masteralloy was also discussed.…”