Study On The Preparation Process Optimization And Properties Of Al-based Bulk Amorphous Alloys

Aluminum-based amorphous alloys have high specific strength,good toughness and excellent corrosion resistance etc.,as a new type of protective coating materials,it is worth promoting.However,due to the glass formation ability(GFA)of aluminum-based amorphous alloy is limited,which hinders its development and application.How to effectively improve the glass forming ability of aluminum-based bulk amorphous alloys,is one of the problems to be solved.In this paper,the Al86Ni6Y4.5Co2La1.5 aluminum-based amorphous alloy composition is studied,the real-time monitoring of the solidification temperature during the preparation of the bulk amorphous alloy is realized by the infrared thermal imager.By studying the solidification microstructure evolution of the aluminum-based amorphous alloys under different processing conditions and studying the relationship between cooling rate and phase evolution,we can determine the optimal processing conditions,which will be used to guide the preparation of aluminum-based amorphous alloys,The results show that the aluminum-based amorphous alloy samples can be prepared under the optimum conditions,and the mechanical properties and corrosion resistance of the samples are evaluated.The main conclusions are as follows:(1)The optimal process parameters of aluminum-based amorphous alloy Al86Ni6Y4.5Co2La1.5 are as follows:the melt temperature is 1050?,the filling speed is 300 mm/s,helium as the melting atmosphere is better,the pressure difference is 0MPa.(2)Under the optimal preparation conditions,the current maximum diameter of 2mm aluminum-based bulk amorphous alloy is prepared successfully;The cooling rates of aluminum-based amorphous bar are 3.3×103K/s,5×103K/s and 9×103K/s at the initial stage of solidification,respectively,from the center to the edge.The cooling rates decrease rapidly with the prolongation of solidification time.The solidification structures are composed of crystal region,composite region and amorphous region from center to edge,The relationship between cooling rate and phase formation is preliminary verified by Flash DSC.(3)Al-based bulk amorphous alloys with different compositions have good corrosion resistance,among which,the corrosion potential of alloy Al86Ni6.75Co2.25Y5 is the highest,about-0.38V,and the pitting potential of Al86Ni7Er5Co1La1is the highest,reaching to-0.15V and the current density is about 10-6 A·cm-2,which is higher than that of pure aluminum and aluminum alloy,which can be protected against corrosion.(4)The hardness of amorphous region is up to 450HV,the hardness of compound region is 570HV,the hardness of crystal region is the lowest,and the hardness is 209HV,which is significantly higher than that of 2024 traditional aluminum alloy(100HV or less).(5)The hardness and elastic modulus of Al86Ni6.75Y3.25Co2.25La1.75 are characterized by nano-indenter,they are 4.7 ± 0.2GPa and 79.3 ± 0.7GPa,respectively,and the hardness value increases with the increase of loading rate.The elastic modulus,On the contrary,declines with the increase of loading rate.