The martensitic transformation of CuAlNi single crystals is measured by DSC (differential scanning calorimeter). An isothermal single interface DO3-->2H transformation arises when the specimen is quenched at a slow...The martensitic transformation of CuAlNi single crystals is measured by DSC (differential scanning calorimeter). An isothermal single interface DO3-->2H transformation arises when the specimen is quenched at a slow rate, but 2H-->DO3 transformation always proceeds with multiple interfaces due to the existence of stored elastic energy inside martensite. The elastic energy is essentially stored on the martensitic interfaces and results in A(s)-->M(f), which brings a separate spectrum of heat flow on the measured curve. The size of stored elastic energy affects the hysteresis.展开更多
The effect of composition and heat treatment on the phase constituent,the size of B2-and DO_3 derived domains and martensitic thermoelastic behaviour in three CuAlNi alloys have been studied by means of metallography,...The effect of composition and heat treatment on the phase constituent,the size of B2-and DO_3 derived domains and martensitic thermoelastic behaviour in three CuAlNi alloys have been studied by means of metallography,TEM anti X-ray diffraction analyses.It is shown that the structure of martensite changes from 18R_1 into 2H and the transition temperature decreases with the increase of the Al content.Moreover,the size of the B2 and DO_3 derived domains decreases with the increase of cooling rate.展开更多
The effect of heat treatment on corrosion properties of CuAlNi shape memory alloy was investigated in 0.9% Na Cl solution at p H 7.4 and 37 ℃ by open circuit potential measurements, polarisation techniques, and elect...The effect of heat treatment on corrosion properties of CuAlNi shape memory alloy was investigated in 0.9% Na Cl solution at p H 7.4 and 37 ℃ by open circuit potential measurements, polarisation techniques, and electrochemical impedance spectroscopy. Investigations were performed on CuAlNi alloy samples in as-cast state and after heat treatment procedure containing annealing at 850, 885 and 920 ℃ followed by water quenching. Electrochemical impedance measurement results indicate that heat treatment of CuAlNi alloy leads to the increase in charge transfer resistance and surface layer resistance and the decrease in values of capacitance of the double and surface layers, indicating higher corrosion resistance compared with the as-cast CuAlNi alloy. The increase in polarisation resistance and the decrease in corrosion current density of heat-treated CuAlNi alloy also suggest beneficial influence of heat treatment on corrosion resistance of CuAlNi alloy. Optical microscopy, SEM/EDX and XRD analysis of samples surface after polarisation measurements show the occurrence of pitting corrosion on the electrode surfaces, with the existence of CuCl2, AlCl3 and Cu2Cl（OH）3 compounds as the surface corrosion products.展开更多
文摘The martensitic transformation of CuAlNi single crystals is measured by DSC (differential scanning calorimeter). An isothermal single interface DO3-->2H transformation arises when the specimen is quenched at a slow rate, but 2H-->DO3 transformation always proceeds with multiple interfaces due to the existence of stored elastic energy inside martensite. The elastic energy is essentially stored on the martensitic interfaces and results in A(s)-->M(f), which brings a separate spectrum of heat flow on the measured curve. The size of stored elastic energy affects the hysteresis.
基金Project supported by National Natural Science Foundation of China
文摘The effect of composition and heat treatment on the phase constituent,the size of B2-and DO_3 derived domains and martensitic thermoelastic behaviour in three CuAlNi alloys have been studied by means of metallography,TEM anti X-ray diffraction analyses.It is shown that the structure of martensite changes from 18R_1 into 2H and the transition temperature decreases with the increase of the Al content.Moreover,the size of the B2 and DO_3 derived domains decreases with the increase of cooling rate.
基金supported by the Croatian Science Foundation under the project IP-2014-09-3405
文摘The effect of heat treatment on corrosion properties of CuAlNi shape memory alloy was investigated in 0.9% Na Cl solution at p H 7.4 and 37 ℃ by open circuit potential measurements, polarisation techniques, and electrochemical impedance spectroscopy. Investigations were performed on CuAlNi alloy samples in as-cast state and after heat treatment procedure containing annealing at 850, 885 and 920 ℃ followed by water quenching. Electrochemical impedance measurement results indicate that heat treatment of CuAlNi alloy leads to the increase in charge transfer resistance and surface layer resistance and the decrease in values of capacitance of the double and surface layers, indicating higher corrosion resistance compared with the as-cast CuAlNi alloy. The increase in polarisation resistance and the decrease in corrosion current density of heat-treated CuAlNi alloy also suggest beneficial influence of heat treatment on corrosion resistance of CuAlNi alloy. Optical microscopy, SEM/EDX and XRD analysis of samples surface after polarisation measurements show the occurrence of pitting corrosion on the electrode surfaces, with the existence of CuCl2, AlCl3 and Cu2Cl（OH）3 compounds as the surface corrosion products.
