论文部分内容阅读
采用铜模喷铸法制备Ti40Zr25Ni8Cu9Be18块体非晶合金,通过分离式霍普金森压杆装置(SHPB)对Ti40Zr25Ni8Cu9Be18块体非晶合金进行室温(25℃)和液氮温度(–196℃)条件下的高应变率加载动态压缩测试,结合S-4800型扫描电镜(SEM)对压缩试样断口进行观察,对比在室温和液氮温度下Ti40Zr25Ni8Cu9Be18块体非晶合金动态压缩性能及其断口形貌特征的差异。结果表明:Ti40Zr25Ni8Cu9Be18块体非晶合金室温动态压缩时,随应变率提高抗压强度无明显变化,没有应变率硬化效应。在液氮温度动态压缩时,抗压强度随着应变率提高有较大幅度增加,存在应变率硬化效应。液氮温度时的动态抗压强度明显高于室温动态抗压强度。Ti40Zr25Ni8Cu9Be18块体非晶合金室温动态压缩为剪切断裂,微观形貌上出现脉状花样和剪切带,剪切带诱发了裂纹的形成,裂纹沿着剪切带扩展。液氮温度下断口微观形貌有解理台阶和河流花样。室温动态断裂过程中,局域应变集中产生塑性变形;液氮温度下压缩动能转化的热量大部分被抵消,削弱了绝热剪切作用。
The Ti40Zr25Ni8Cu9Be18 bulk amorphous alloy was prepared by copper mold casting method. The bulk amorphous alloy Ti40Zr25Ni8Cu9Be18 was subjected to room temperature (-25 ℃) and liquid nitrogen temperature (-196 ℃) by the split Hopkinson pressure bar device (SHPB) The dynamic compression test of Ti40Zr25Ni8Cu9Be18 bulk amorphous alloy at room temperature and liquid nitrogen temperature was compared with S-4800 scanning electron microscope (SEM) to observe the dynamic compression characteristics and fracture surface morphologies of Ti40Zr25Ni8Cu9Be18 bulk amorphous alloy The difference. The results show that when the Ti40Zr25Ni8Cu9Be18 bulk amorphous alloy is dynamically compressed at room temperature, there is no obvious change in compressive strength with strain rate and no strain rate hardening effect. When the temperature of liquid nitrogen is dynamically compressed, the compressive strength increases with the increase of strain rate, and there is strain hardening effect. The dynamic compressive strength at liquid nitrogen temperature is significantly higher than the dynamic compressive strength at room temperature. Dynamic compressive deformation of Ti40Zr25Ni8Cu9Be18 bulk amorphous alloy at room temperature is shear fracture, and vein patterns and shear bands appear on the microstructure. The shear band induces the formation of cracks, which propagate along the shear band. The microstructure of fracture surface at solution temperature has cleavage steps and river pattern. During the dynamic rupture at room temperature, local strain concentrates and produces plastic deformation. Most of the heat converted by the compression kinetic energy at liquid nitrogen temperature is offset, which weakens the adiabatic shear effect.