Study On Al-Y-(Ti,B) Amorphous Refiner For Aluminum Alloy

Aluminum alloy has high specific strength,light weight,good electrical and thermal conductivity,excellent corrosion resistance and excellent processing performance,in aerospace,automotive industry,construction and other industries have been widely used.With the development of science and technology,it is urgent to improve the comprehensive mechanical properties of aluminum alloy to meet the complex and changeable service environment.Grain refinement is an effective method to improve the comprehensive mechanical properties of aluminum alloy.Currently,the most widely used aluminum alloy refiner is Al-Ti-B alloy.However,due to the fact that Ti B₂ particles,which play a refining role,tend to aggregate and cause precipitation,are also poisoned by Zr,Cr and other elements,which attenuate the refining effect.Therefore,it is an urgent problem to develop a new type of refiner for aluminum alloy.In this paper,three kind of amorphous refiners Al₉₀Y₁₀,Al₈₈Y₁₀B₂ and Al₉₀Y₈Ti₂were prepared by liquid metal quench method.The amorphous alloy was characterized by XRD and DSC.OM,SEM,XRD,EDS and other testing methods were used to characterize A356 aluminum alloy and analyze its refining mechanism.The mechanical properties of A356 aluminum alloy were characterized by universal testing machine and Vickers hardness tester.The following conclusions were reached:(1)Amorphous intermediate alloy Al₉₀Y₁₀ had the best refining effect on A356 aluminum alloy when the addition of refiner was 0.6 wt.%and the holding time was 10min.At this time,the tensile strength,yield strength,elongation and hardness of A356 aluminum alloy were increased by 12.5%,16.67%,30.51%and 17.66%,respectively,compared with that before refining.(2)Amorphous intermediate alloy Al₈₈Y₁₀B₂had the best refining effect on A356 aluminum alloy when the addition of refiner was 0.6 wt.%for 10 min of holding time.At this time,the tensile strength,yield strength,elongation and hardness of A356 alloy were increased by 22.49%,14.05%,21.67%and 38.33%,respectively,compared with that before refining.(3)Amorphous intermediate alloy Al₉₀Y₈Ti₂ had the best refining effect on A356 aluminum alloy when the holding time was 5 min and the adding amount of refiner was0.2 wt.%.At this time,the tensile strength,yield strength,elongation and Vickers hardness of A356 alloy were increased by 26.13%,11.71%,12.4%and 25.83%,respectively,compared with that before refining.(4)After adding refiner,the aggregation phase of rare-earth element Y will be formed between the?-Al phase and eutectic silicon phase of A356 aluminum alloy,preventing the exchange of two phase solute and refining two phase grains.At the same time,the phase is rich in Fe impurities,reducing Fe brittle phase precipitation in the alloy matrix.After Ti and B elements are added,heterogeneous nucleation particles such as AlB₂,YAl₃ and Al₃Ti will be formed to participate in the heterogeneous nucleation process of?-Al phase to increase the number of nucleation,refine grains and improve the strength of the alloy.(5)Compared with the amorphous intermediate alloy,the orderly crystal structure of the crystalline intermediate alloy leads to poor tensile fracture morphology in the melt of A356 aluminum alloy,resulting in a slight decrease in the strength and plasticity of the alloy.