Dynamic Mechanical Behavior And Penetration Properties Of Hafnium-based Amorphous Alloys

Amorphous alloys have excellent mechanical,physical and chemical performances,and have a very broad application prospect in the field of military and civilian applications.Some amorphous alloys containing active elements can stimulate chemical reactions and release energy under high temperature and high pressure,so that they become very promising materials in the field of national defense,especially in the direction of high-efficiency damage.The material is expected to be applied to the core of new armor-piercing projectile and fragments for high-efficiency damage,and gradually becomes a hot research field of high-speed armorpiercing and armor protection.The static and dynamic mechanical behavior and penetration performance of typical Hf-based amorphous alloy are studied in the present thesis.The static and dynamic mechanical properties tests of Hf-based amorphous alloy and the penetration test of Hf-based amorphous alloy jacketed rod with tungsten alloy sleeve on semi-infinite target are carried out.Based on the penetration model of homogeneous long-rod projectile,the penetration depth and pit diameter of the jacketed rod are calculated.The factors which has influence on the penetration performance of jacketed rod are studied by numerical simulation method.The main research contents are as follows:(1)Study on the characteristics of static and dynamic mechanical behavior and failure of Hf-based amorphous alloy materials.Adopting the material testing machine and the Split Hopkinson Pressure Bar(SHPB)test platform,the quasi-static and dynamic compression tests of Hf-based amorphous alloys were conducted to study the mechanical response of materials under different strain rates.The fracture morphology of Hf-based amorphous alloy samples after the test was characterized by SEM,and the impact failure mechanism of Hf-based amorphous alloy materials was analyzed.The results show that Hf-based amorphous alloy can maintain high fracture strength at low and medium strain rates,and the material exhibits a feature of brittle fracture,while the fracture strength of the material is negatively correlated with the strain rate under dynamic compression.The high-speed video results of the compression process and the fracture morphology of the specimen show that the material fracture process is accompanied by reaction.(2)Experimental study on Hf-based amorphous alloy jacketed rod penetrating semiinfinite thick target.Jacketed rod with tungsten alloy as the sleeve and 45 steel and Hf-based amorphous alloy as the core was designed.The penetration tests of the jacketed rod against 45 steel target and concrete target were carried out.According to the image captured by high-speed camera,the phenomenon of impact energy release of Hf-based amorphous alloy during the penetration process of the jacketed rod was analyzed.A comparison of the penetration performance between two types of jacketed rods was presented,and the damage enhancement effect of Hf-based amorphous alloy in the high-speed penetration of the jacketed rod was discussed.The results show that the Hf-based amorphous alloy jacketed rod has an obvious energy release phenomenon in the process of penetrating the 45 steel target,which significantly improves the penetration depth and hole diameter of the projectile.The Hf-based amorphous alloy strengthens the damage effect of projectile in the process of penetrating concrete target,resulting in a large area of collapse of the target surface,increasing the crater depth and crater volume of the target,and increasing the penetration depth of the projectile.(3)Analytical model of the interaction process of jacketed rod penetrating semi-infinite target.The penetration mode of the jacketed rod penetrating into the semi-infinite metal target is analyzed,and the model for calculating the penetration depth and the opening radius of the jacketed rod penetrating into the semi-infinite target is improved.Based on the law of energy conservation,the energy released by the reaction of the Hf-based amorphous alloy material is added to the penetration model,and the engineering model for calculating the opening radius considering the energy release effect of Hf-based amorphous alloy is established.It shows that the calculation results of the model are in good agreement with the experimentaldata.(4)Numerical simulation of jacketed rod penetrating semi-infinite steel target.The parameters in constitutive model of Hf-based amorphous alloy JH-2 were determined based on the literature research and experimental results fitting.The numerical simulation of jacketed rod penetrating into semi-infinite thick steel target was carried out by AUTODYN software.Combined with the results of penetration test,the reliability of the material constitutive model,parameters and numerical model was verified.The influence of projectile parameters,like the sleeve and the core material,the sleeve and the core diameter ratio of the jacketed rod,on the penetration performance of the jacketed rod were investigated and discussed.