Research On Optical Thermometry In The Preparation Of Nb₃Al Superconducting Wire

Nb3Al superconductors are considered to have good application prospects in the field of next-generation high-field superconducting magnets due to their superior high field performance,good ductility and ability to withstand stress and strain.Using Nb3Al precursor produced by Jelly-Roll(JR)method,combined with the rapid heating and quenching transformation(RHQT)method,A few developed countries such as the United States and Japan have produced Nb3Al superconducting wire with superior performance.But it has not reached the level of practical mass production.And there are still some problems to be solved.The phase composition of Nb-Al is complicated,and the phase interval of Nb3Al is narrow in the equilibrium phase diagram.However,the temperature detection of Nb3Al precursor in the rapid heating and quenching process abroad is relatively rough,so it is difficult to study the specific phase transition law of Nb3Al precursor in this process.To study the specific phase transition law of Nb3Al precursor in RHQT process,this thesis developed a Charge-coupled Device(CCD)colorimetric temperature measuring device.The device uses a TCD2252D model CCD as a radiation collection tool to measure the radiation intensity of the Nb3Al precursor during RHQT process,and to output RGB signal values,and uses a STM32F103C8T6 model ARM chip to receive RGB signals and to process it with colorimetric temperature measurement method.And then combine with the Visual Basic program to detect the temperature.The device has a fast temperature measurement rate which ups to 10 kHz.After calibration,its temperature measurement accuracy is within±40? when the temperature is between 1800 ? and 2500 ?.Using the device for measurement,the trend of the temperature of the Nb3Al precursor during RHQT process can be clearly demonstrated.Then,the phase formation law of Nb3Al can be better studied.And we can also work out a more targeted treatment scheme,according to the difference of the precursor,which can control the temperature in the RHQT process accurately,so as to improve the performance of the superconductor.The successful development of the temperature measuring device solves a key problem in studying the phase transition law of Nb3Al.In this paper,the developed CCD colorimetric temperature measuring device is mainly used for the precursor produced by PIT method,which is easier to mass-produce,and is supplemented by the precursor produced by JR method.The phase transition law of Nb3Al was studied.It was verified that the process of generating BCC(Body-Centered Cubic)phase near 1940? was endothermic and reversible.The best method,RHQT method was improved to produce Nb3Al superconducting phase.