Crystallization Kinetics Of Multiple Hafnium-based Amorphous Alloys Study On Dynamic Mechanical Properties

Hf-based amorphous alloys are widely used in aerospace,electronic devices and other fields due to their excellent properties such as high strength,high hardness,and corrosion resistance.However,Hf-based amorphous alloys have poor glass-forming ability and brittle fracture at room temperature,limiting their development in the engineering field.In this paper,the elements of Cu and Ni in the Hf-Be-Ti-Zr-Cu-Ni amorphous alloy were replaced with Ti and Zr elements,respectively,so as to prepare Hf-based amorphous alloys with strong glass-forming ability.Crystallization kinetics of Hf-based amorphous alloys,and the fracture behavior of Hf-based amorphous alloys at high strain rates was analyzed.The main results of the paper are as follows:In the Hf₂₆Be₁₈Ti_10+2xZr₁₈Cu_11.5-xNi_16.5-x amorphous alloy system,the effect of replacing Cu and Ni with Ti element on the glass-forming ability of the amorphous alloy was studied.It is concluded that when the composition of the amorphous alloy is Hf₂₆Be₁₈Ti₁₀Zr₁₈Cu_11.5Ni_16.5,it has a wide supercooled liquid range of 46.17 K,and the glass transition temperature T_rg is 0.6312,the?parameter is 0.4139,the density is 8.3856 g/cm~3,and the hardness is 642 HV,indicating that the alloy has strong lass-forming ability.In the Hf₂₆Be₁₈Ti₁₈Zr_10+2xCu_11.5-xNi_16.5-x amorphous alloy system,the effect of replacing Cu and Ni with Zr element on the glass-forming ability of the amorphous alloy was studied.When the alloy composition is Hf₂₆Be₁₈Ti₁₈Zr₁₀Cu_11.5Ni_16.5,the supercooled liquid phase interval value reaches the maximum value of 58.41K,and the reduced glass transition temperature is T_rg 0.6333,the?parameter is 0.4139,the density is 8.4856 g/cm~3,and the hardness is 638 HV,indicating that the alloy has strong lass-forming ability.The crystallization kinetics and annealing behavior of Hf₂₆Be₁₈Ti₁₈Zr₁₈Cu_7.5Ni_12.5amorphous alloy were studied.The result is:under non-isothermal conditions,the amorphous alloy has significant crystallization kinetics effect.And the E_p of the amorphous alloy is greater than E_x,indicating that the activation energy of crystal growth is greater than that of crystal nucleation during the whole crystallization process.In isothermal conditions,with the increase of the holding temperature,the incubation period of the amorphous alloy gradually shortened,which has a significant kinetic effect.When the crystallization volume fraction increases,the activation energy shows a decreasing trend.The range of Avrami index n is calculated to be between 1.38 and 1.56,and it is concluded that the crystallization process of the amorphous alloy is the growth of the diffusion process.The isothermal annealing study of Hf₂₆Be₁₈Ti₁₈Zr₁₈Cu_7.5Ni_12.5 amorphous alloy was carried out.When the annealing temperature increased from 593 K to 673 K,the crystallization peak of the alloy became more significant,the crystallization phenomenon was serious,and the hardness value after isothermal annealing also changed from 610 HV increased to 642 HV,an increase of about 5%.The mechanical properties of Hf₂₆Be₁₈Ti_10+2xZr₁₈Cu_11.5-xNi_16.5-x amorphous alloy system and Hf₂₆Be₁₈Ti₁₈Zr_10+2xCu_11.5-xNi_16.5-x amorphous alloy system at room temperature were studied.It is concluded that Hf₂₆Be₁₈Ti₁₀Zr₁₈Cu_11.5Ni_16.5,Hf₂₆Be₁₈Ti₁₄Zr₁₈Cu_9.5Ni_14.5,Hf₂₆Be₁₈Ti₁₈Zr₁₈Cu_7.5Ni_12.5,Hf₂₆Be₁₈Ti₁₈Zr₁₀Cu_11.5Ni_16.5 and Hf₂₆Be₁₈Ti₁₈Zr₁₄Cu_9.5Ni_14.5 amorphous alloys all exhibit brittle fracture.It exhibits high strength,with fracture strength ranging from 1616.40 MPa to 2484.19 MPa.Among them,the fracture strength of Hf₂₆Be₁₈Ti₁₈Zr₁₀Cu_11.5Ni_16.5 amorphous alloy is the highest,reaching 2484.19 MPa,while the fracture strength of Hf₂₆Be₁₈Ti₁₈Zr₁₈Cu_7.5Ni_12.5 amorphous alloy is relatively the lowest,which is 1616.40 MPa.Among them,Hf26Be18Ti10Zr18Cu11.5Ni16.5,Hf26Be18Ti14Zr18Cu9.5Ni14.5 and Hf26Be18Ti18Zr10Cu11.5Ni16.5amorphous alloy have a small amount of plastic deformation,but the overall is still brittle fracture.The dynamic mechanical properties of Hf₂₆Be₁₈Ti₁₈Zr₁₈Cu_7.5Ni_12.5 amorphous alloy and Hf₂₆Be₁₈Ti₁₈Zr₁₀Cu_11.5Ni_16.5 amorphous alloy were studied.It can be concluded that:When the strain rate gradually increases,the fracture strength shows a downward trend,indicating that both alloys show negative strain rate sensitivity.For the Hf₂₆Be₁₈Ti₁₈Zr₁₈Cu_7.5Ni_12.5 amorphous alloy,when the strain rate is 1380 s^-1,the fracture strength is 1210.22 MPa,and when the strain rate increases to 1950 s^-1,the fracture strength decreases to 1010.97 MPa.For the Hf₂₆Be₁₈Ti₁₈Zr₁₀Cu_11.5Ni_16.5 amorphous alloy,when the strain rate is 450 s^-1,the fracture strength is as high as1690.76 MPa,while when the strain rate increases to 1500 s^-1,the fracture strength decreases to1154.35 MPa,which indicates a higher strength.Furthermore,the preparation process of the Hf₂₆Be₁₈Ti₁₈Zr₁₀Cu_11.5Ni_16.5 amorphous alloy conical shell with higher strength was studied.When the casting temperature is 1200°C and the casting speed is 2s,it is more conducive to the formation of complete filling amorphous structure.