Effect of Y Element on Microstructure and Hot Tearing Sensitivity of As-Cast Al–4.4Cu–1.5Mg–0.15Zr Alloy

Abstract

In this paper, the effect of Y content on hot tearing properties of cast Al-Cu-Mg alloy was studied. The effect and mechanism of Y on hot tearing of cast Al-4.4Cu-1.5Mg-0.15Zr alloy were studied by analyzing the microstructure evolution, phase structure, solidification process and hot tearing sensitivity coefficient of the alloy with different Y additions, and determined the appropriate amount of Y element. The results showed that Y improves hot tearing resistance of Al-4.4Cu-1.5Mg-0.15Zr alloy by refining microstructure and reducing the solidification temperature range. The suitable amount of Y is 0.15 wt%. At this time, a certain amount of Al 6 Cu 6 Y low melting point phase is formed in the alloy, and the grain structure is the smallest, which significantly improves the hot tearing resistance of Al-4.4Cu-1.5Mg-0.15Zr alloy. The microstructure coarsening and hot tearing tendency increase with increasing Y content. The experimental results are basically consistent with the hot tearing sensitivity predicted by the Clyne-Davies model.

The Influence of Alloying Elements on the Microstructure and Properties of Al-Si-Based Casting Alloys: A Review

“…However, RE elements were also observed to increase the solidification interval in Al-Si alloys, in addition to reducing the nucleation temperature of the eutectic phase and increasing undercooling [125]. The use of RE can also reduce the tendency of hot tearing susceptibility during casting [126]. Adding rare earths can also bring positive effects to corrosion resistance because they form stable, protective oxides on the surface of the part [18,127].…”

“…Above that, in addition to increasing hot tearing susceptibility, the element also promotes microstructural coarsening, and the effect of reduction of the solidification interval is damped. The deleterious role of excessive Y can be explained by the precipitation of coarse (Al,Y)-rich particles that tend to agglomerate, hindering feeding of liquid metal [126]. Table 6 summarizes optimized compositions obtained by the addition of transition elements and their respective properties.…”

Effect of yttrium content on microstructure and tensile properties of as-cast and as-solutionized Al-Zn-Mg-Cu alloys

“…According to the as-cast structure pictures of the four alloys in figure 3, when the content of Y increases from 0 wt% to 0.45 wt%, the second phases of as-cast alloy become more uniform, but 0.75Y alloy somewhat anomalously. This may be the increase of yttrium content shortens the solidification temperature range of aluminum alloy [12]. The intergranular phases of as-cast 0Y alloy is almost Mg(Zn, Cu, Al) 2 lamellar phases, the increased Y element forms bulk-like (Al, Zn) 8 Cu 4 Y phases at interdendrites.…”