Effect of Al-5Ti-0.62C-0.2Ce Master Alloy on the Microstructure and Tensile Properties of Commercial Pure Al and Hypoeutectic Al-8Si Alloy

Abstract

Al-5Ti-0.62C-0.2Ce master alloy was synthesized by a method of thermal explosion reaction in pure molten aluminum and used to modify commercial pure Al and hypoeutectic Al-8Si alloy. The microstructure and tensile properties of commercial pure Al and hypoeutectic Al-8Si alloy with different additions of Al-5Ti-0.62C-0.2Ce master alloy were investigated. The results show that the Al-5Ti-0.62C-0.2Ce alloy was composed of α-Al, granular TiC, lump-like TiAl3 and block-like Ti2Al20Ce. Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min) can significantly refine macro grains of commercial pure Al into tiny equiaxed grains. The Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 30 min) still has a good refinement effect. The tensile strength and elongation of commercial pure Al modified by the Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min) increased by roughly 19.26% and 61.83%, respectively. Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min) can significantly refine both α-Al grains and eutectic Si of hypoeutectic Al-8Si alloy. The dendritic α-Al grains were significantly refined to tiny equiaxed grains. The morphology of the eutectic Si crystals was significantly refined from coarse needle-shape or lath-shape to short rod-like or grain-like eutectic Si. The tensile strength and elongation of hypoeutectic Al-8Si alloy modified by the Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min) increased by roughly 20.53% and 50%, respectively. The change in mechanical properties corresponds to evolution of the microstructure.

Effects of In-Situ Reaction, Extrusion Ratio and CeO2 on the Performance of Al-Ti-C-(Ce) Grain Refiners for Refining Pure Aluminum Grains

“…However, the Al-Ti-C-Ce grain refiner did not show the phenomenon of grain-refining fading. This result is related to the Ti 2 Al 20 Ce phase and [Ce] atoms coated on the surface of TiAl 3 and TiC, thus prolonging the nucleation time of the second phase in Al melt [ 16 , 23 ]. With severe grain-refining fading, the average size of pure aluminum grains increased to 116.4 μm and 68.4 μm after holding for 10 min.…”

“…∆G 3 < 0, evenly distributed CeC 2 particles react to generate TiC and the released [Ce] atoms (reaction (4)) ( Figure 16 b). [Ce] atoms adsorb on the surface of TiAl 3 , and the reaction (5) forms a core-shell structure of Ti 2 Al 20 Ce coated on TiAl 3 [ 18 ] ( Figure 16 c), which inhibits the growth of TiAl 3 phase crystal nuclei and promotes α-Al nucleation [ 16 , 23 ] ( Figure 16 d). In the meantime, part of the Ti 2 Al 20 Ce phase continuously releases [Ce] atoms [ 17 ] into the melt during the holding process.…”

Grain Refinement of Al-5Ti-0.62C-0.2Nd Grain Refiner for Commercial Pure Aluminum and Its Effect on Mechanical Properties

“…On the other side, the layer guarantees that even tiny TiC particles cannot easily precipitate together. The uniform distribution of TiC in the aluminum melt in a suspended state not only can fully undertake the role of the nucleation core, but can also provide a good grain-refinement recession and guarantee a long-term refining effect 26,27 .…”

Effect of CeO2 on Microstructure and Synthesis Mechanism of Al-Ti-C Alloy

“…Moreover, the author’s previous research found that the preparation of Al-Ti-C-Ce alloy by in-situ reaction of aluminum melt with CeO 2 as an additive cannot only reduce the production cost, but also improve the refining performance of Al-Ti-C alloy [18,23]. However, the mechanism of rare earth oxides in the preparation of Al-Ti-C-RE alloys is still unclear [24,25,26,27,28], and there is a lack of systematic and in-depth research on the thermodynamics and kinetics of synthesis reactions.…”