Research On Preparation Of Ti-based Amorphous Alloys And Process Optimization Of Mechanical Alloying

Ti-based amorphous alloy has the advantages of low density,high strength,corrosion resistance and other excellent performance.It is widely used in biomedical medicine industry and military industy such aerospace,etc.,but the shortcomings including too small size and worse plasticity restrict its development.Discontinuous reinforced titanium matrix composites not only retain the good plasticity of matrix,but also promote the strength of the material at the interfaces,and it has been rapidly developed in recent years.Therefore,this article explores the preparation technology of Ti-based amorphous alloy powder,and takes it as reinforced phase composite materials which has important theoretical significance and practical value.We used Single roller spinning quenching method and melting injection method to prepare amorphous alloy,Ti_41.5Zr_2.5Hf₅Cu_42.5-xNi_7.5Si₁Sn_x?x = 0,1,3,5,7?and used XRD/DSC to analyze its GFA.The alloy's micro-structure and properties were analyzed by using SEM and mechanical property test.Amorphous alloy powders,Ti_41.5Zr_2.5Hf₅Cua_7.5Ni_7.5Si₁Sn₅,were prepared,and the heat treatment process and ball milling process were studied and optimized.Accodring to the study of different alloy component,we found that Ti_41.5Zr_2.5Hf₅Cu_37.5Ni_7.5Si₁Sn₅ exhibits a wide supercooled liquid region and a plurality of crystallization exothermic peaks.In GFA criterion,Tx=64.19K,Trg=0.590,?=0.405,?=1.569.According to the XRD spectrum,the alloy has a strong ability of amorphous formation.The room temperature compressive strength of 1.5mm amorphous rod reaches 2303.93Mpa,the micro-hardness is 546.02Hv,the modulus is 143.83Gpa.So it shows excellent mechanical properties.The crystallization of Ti_41.5Zr_2.5Hf₅Cu_37.5Ni_7.5Si₁Sn₅ amorphous alloy was analyzed.The first stage of crystallization was initiated at 485 °C.The XRD spectrum showed a small diffraction peak at about 20around 41°,and the Cu Ti phase was precipitated.The intensity of the diffuse scattering peak decreased and the range becomed narrow.The second stage of crystallization occurred at 580 ?.??Cu,Sn?,CuTi phase,and Ni₂SnZr and other components,was precipitated.At 685 ?,the crystallization process was basically completed,and the Hf14Cusi phase was precipitated.The effects of different quenching temperature and holding time on the microstructure and properties of the alloy were studied.And we performed XRD,DSC and hardness and brittleness test.With the increase of temperature and time,the hardness and brittleness of the alloy increased gradually.At 422 ? or 8min,the alloy began to crystallize.When the quenching temperature was 410? and the holding time was 5min,the alloy could meet the requirements of later powder preparation.The ball milling process with different time,rotational speed and ball material ratio was studied.Taking SEM,XRD,DSC and Nano Measurer as the analysis method,for the purpose of refining the powder size,distributing it evenly,and ensuring that the alloy was amorphous,the alloy powder with average particle size of about 90?m and uniform distribution,was prepared by the technology of ball to material weight ratio 20:1,rotating speed at 175r/min and milling time for 50h.The nanoindentation test was carried out on amorphous alloy bar,strip and powder.The hardness of the alloy powder was 14.03Gpa,which was increased by 3.2%and 35.1%compared with the hardness of the strip and the bar.The mechanical properties of alloy powder are more excellent.