Effect of Al-TiO2-C-XY2O3 refiner on grain size and mechanical properties of Al-5Cu alloy

A series of new Al-TiO 2 -C-Y 2 O 3 aluminum alloy grain refiners with different Y 2 O 3 content was prepared by exothermic dispersion method using Al, TiO 2 , C, and Y 2 O 3 powders as raw materials. Scanning electron microscopy (SEM), x-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS) were used to investigate the effect of Y 2 O 3 content on the structure of the Al-TiO 2 -C refining agent as well as the effect of the Al-TiO 2 -C-Y 2 O 3 refining agent on the grain size and mechanical properties of an Al-5Cu alloy. The results showed that the Al-TiO 2 -C-Y 2 O 3 refiner was composed of Al 2 O 3 , TiC, Al 3 Ti, Al 5 Y 3 O 12 , and Al 20 Ti 2 Y phases. The refiner with 4% Y 2 O 3 content exhibited the best Al-5Cu alloy refining effect, achieving a grain size of about 210.5 μ m. This was about 42% of the grain size of the original Al-5Cu alloy. Moreover, this refined Al-5Cu alloy exhibited the best mechanical properties, with a tensile strength and elongation of 173.13 MPa and 9.19% respectively. This was a 20.9% and 83.8% improvement compared with the original Al-5Cu alloy. However, with a further increase in Y 2 O 3 content, an Al 5 Y 3 O 12 phase was preferentially formed. This led to a decline in Al 20 Ti 2 Y phase content and a correspondingly weaker refinement effect.