The Study Of Microstructures And Tribological Properties Of Ti-based Metallic Glass Matrix Composites

Bulk metallic glasses（BMGs）obtained wide attention of many scholars both at home and abroad with follow-up research and reports due to their unique properties,such as high strength,high hardness and excellent soft magnetic properties.However,BMGs generally do not exhibit any significant macroscopic plasticity upon loading,since the plastic deformation is highly localized in narrow regions termed shear bands,which greatly limits its engineering application prospect.After a long period of research,scientists have developed a series of dendrite-reinforced metallic glass matrix composites（MGMCs）by adjusting the composition and using appropriate cooling process,which have excellent properties of BMGs and good room temperature ductility,so it has a broad application prospect.This paper mainly studied the microstructure and tribological properties in different environments of Ti-based MGMCs.In this paper,the four Ti-based MGMCs with different components were prepared using the WKFEI non-consumable vacuum arc furnace: Ti₄₀Zr₂₄V₁₂Cu₅Be19,Ti₅₂Zr₂₂V₁₀Cu₄Be₁₂,Ti₅₆Zr₁₈V₁₀Cu₄Be₁₂ and Ti58Zr16V₁₀Cu₄Be₁₂.After that,the hardness of the composites was measured by HVS-₁₀00 Vickers hardness test.The phase composition and microstructure of Ti-based MGMCs were analysed by the metallographic microscope,Ricoh D/MAx-RB X-ray diffractometer,and JEOL JMS-6390 scanning electron microscopy（SEM）analysed,and the volume fraction of the dendrite phase was calculated.The friction and wear properties of the four composites under dry environment,deionized water and acid rain were conducted by the MFT-R₄₀00 reciprocating friction and wear testing machine.The effect of Load,friction environment and dendrite volume fraction on the tribological properties of MGMCs was investigated in detail.The conclusions are as follows:（1）The dendrite volume fraction of the four composites Ti₄₀Zr₂₄V₁₂Cu₅Be19,Ti₅₆Zr₁₈V₁₀Cu₄Be₁₂,Ti₅₂Zr₂₂V₁₀Cu₄Be₁₂ and Ti58Zr16V₁₀Cu₄Be₁₂ are 55%,57%,61% and 63%,respectively,the hardness of the composites decreases with the increase of the dendrite volume fraction,which was 6₂₂,514,4₂₂ and ₄₀8 HV,respectively.（2）In the dry environment,The wear rate of Ti₄₀Zr₂₄V₁₂Cu₅Be19 composites was decreased linearly and achieved a minimum of 2.73×₁₀-4 mm3/（N m）at 17 N.Nevertheless,the wear rate of other Ti-based composites was all decreased and reached a minimum with increasing the normal load,then increased.The wear rate of Ti₅₂Zr₂₂V₁₀Cu₄Be₁₂ and Ti₅₆Zr₁₈V₁₀Cu₄Be₁₂ composites reached a minimum of 3.99 and 2.64 × ₁₀-4 mm3/（N m）at ₁₀ N,respectively.And the wear rate of Ti58Zr16V₁₀Cu₄Be₁₂ composites obtained a minimum of 4.68 × ₁₀-4 mm3/（N m）at 5 N.The wear mechanisms of current Ti-based MGMCs was dominated by abrasive and adhesive wears.Oxidation happened during wear.The oxidation products mainly included TiO2,ZrO2 and Cu2 O.（3）In the deionized water and acid rain environment,the wear rate law of the four Ti-based MGMCs is the same as that of dry friction.The wear rate of Ti₄₀Zr₂₄V₁₂Cu₅Be19 composites was decreased linearly with increasing the normal load,while the wear rate of other Ti-based composites was first decreased and then increased.The results indicated that in the process of friction and wear,the tribological properties of the MGMCs is mainly affected by normal load,oxide protective film and friction heat.When the hardness of the composites is larger,the main factor is the normal load,when the hardness of the composites is smaller,the main factor is the normal load at low normal load,while the main factor is oxidation protection film and friction heat at high normal load.（4）The wear rate of the four Ti-based MGMCs in the deionized water is smaller than that of the composites in the dry environment,indicating that the lubrication effect of deionized water can reduce wear.The wear rate of the composites in the acid rain is larger than that of the composites in the dry environment,which indicates that the corrosion of acid rain will increase the wear and tear,and the synergistic effect between corrosion and wear will accelerate the wear.Oxidation and corrosion occurred during the process of the wear tests in the acid rain,which accelerated the wear.The major oxidation products were ZrO2,TiO2,and Cu2 O,and the major corrosion products were metal chloride,metal carbonate,and metal sulfate.（5）The results show that Ti₅₂Zr₂₂V₁₀Cu₄Be₁₂ and Ti58Zr16V₁₀Cu₄Be₁₂ composites have poorer wear resistance and better corrosion resistance than Ti₄₀Zr₂₄V₁₂Cu₅Be19 and Ti₅₆Zr₁₈V₁₀Cu₄Be₁₂ composites.The increase of the dendrite volume fraction will reduce the wear resistance but improve the corrosion resistance of the composites.