Synergistic Effects of La and Y on the Microstructure and Mechanical Properties of Cast Al-Si-Cu Alloys

Abstract

The effects of La and Y on the microstructure and mechanical properties of cast Al-Si-Cu alloys were investigated by X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM). The results indicated that the addition of La and Y had a great effect on the refinement of α-Al grains, the modification of eutectic Si phase, and the reduction of β-Al5FeSi length in Al-Si-Cu alloys. The A380 + 0.6 wt.% La/Y alloy exhibited the best microstructure and mechanical properties. The UTS and EI of the A380 + 0.6 wt.% La/Y alloy were 215.3 MPa and 5.1%, which were 22.9% and 37.8% higher than those of the matrix alloy, respectively. In addition, neither Al11La3 nor Al3Y generated by the addition of La and Y could not serve as the nucleation core of α-Al grains, so the grain refinement of α-Al originated from the growth limitation and constitutional supercooling. Since La and Y promote twinning generation and constitutional supercooling, the eutectic Si phase also changed from stripe-like to short fibrous or even granular and was significantly refined. Furthermore, thermodynamic calculations indicated that the Al11La3 phase was formed first and the Al3Y phase was generated on the Al11La3 phase.

Dispersoids in Al-Mg-Si Alloy AA 6086 Modified by Sc and Y

“…Yttrium strongly reduces grain sizes in Al-Si alloys during solidification [30]; thus, an Al-Y-B grain refiner was developed [31]. It also modifies the eutectic silicon and iron-rich phases in Al-Si-Cu and Al-Si piston alloys [32][33][34]. Shen et al [35] investigated the effect of Y on the properties of Al-Mg-Mn alloys.…”

Effect of Combined Addition of CeLa and GdY on Microstructure and Mechanical Properties of As-Cast Al-Cu-Mn Alloys

“…The literature has reported the effect of the combined addition of CeLa [31,32], LaY [33], CeY [34], LaPr [35], and LaSc [36] on the microstructure and properties of Al-Cu alloys. The results show that binary combined additions of Re have a significant effect on the grain refinement of the alloy.…”

“…Their findings indicated that CeLa could increase melt subcooling by inhibiting the nucleation of α-Al on large heterogeneous particles, resulting in grain refinement. Shuai et al found that when 0.6 wt.% LaY was added to the Al-Si-Cu alloy, the SDAS of α-Al decreased to 77.56 µm, which is 75.11% lower than Al-Si-Cu [33]. Furthermore, binary combined additions of Re demonstrated better performances than single additions of rare earth elements.…”

Advances in High-Performance Non-Ferrous Materials

“…Wang et al [ 4 ] unraveled the microstructure–mechanical properties relationship of the W–Al 2 O 3 composite that was prepared via induction sintering and rolling processes. Shuai et al’s work revealed the alloying elements’ (i.e., La and Y) effects on the microstructure and mechanical properties of cast Al–Si–Cu alloys [ 5 ]. The addition of La and Y had an evident effect on refining and/or modifying α-Al grains, the eutectic Si phase, and β-Al 5 FeSi intermetallics.…”