Development Of High-throughput Thermal Analysis To Study Fast Phase Transition Of Thin-film Alloys

High-throughput Experimental method,as a key component of the material genome project,can accelerate the pace of discovery and the deployment of advanced materials by providing combinatorial approaches to produce and characterize materials.However,the developed methods used to study alloy systems are very limited,and most experimental methods can only achieve rapid screening of materials based on qualitative characterization.Here we study two complementary high-throughput thermal analysis methods,nanocalorimetry and temperature-resistance measurement,to synthesize materials library using thin-film composition spreads and quantitatively analyze thermal properties in parallel.Specifically,nanocalorimetry can measure the heat capacity of thin film and the enthalpy of phase change or chemical reaction,and temperature-resistance measurement is able to indicate the microstructure changes directly.We first design and fabricate sensor arrays of nanocalorimetry and temperature-resistivity individually.We then study the data analysis,develop electronical and mechanical systems and provide sample preparation and characterization methods based on the sensor arrays.A differencial nanocalorimetry method,with high sensitivity and low electrical noise,is presented.Results show that nanocalorimetry sensor arrays are capable to perform in-situ heat treatment on the individual sensor and collect thermal information synchronously.Sensors can work at 1500 K,with a scan rate as high as 10⁵ K/s.We develop differential nanocalorimetry technich to achieve an excellent sensitivity of 12pJ/K,which provides a method to measure subtle phase change of thin films.Attributed to the fast scanning rate,nanocalorimety can not only save time of the measurement but also provides an effective method for studying rapid phase change and kinetics of phase change.We have developed sensor arrays using a simple and inexpensive fabrication process to measure the electrical resistance of thin-film materials as a function of temperature and composition.The sensors are capable of characterizing materials from liquid-nitrogen temperature to approximately 1000 K and are not limited by low sample conductivity.The temperature non-uniformity of the sensor is better than 0.112%at temperatures below 1000 K,which makes it possible to detect subtle phase change of thin films.Based on the two high-throughput methods of thermal analysis,we study phase changes of metallic glasses and shape memory alloys.On the one hand,we use nanocalorimetry to study phase evolutions of Cu₅₀Zr₅₀,the crystallization behavior and the martensitic phase change of CuZr.Nanocalorimetry result of Cu₅₀Zr₅₀0 shows that by changing the temperature to which a sample is heated,the resulting sample may,on cooling,contain a significant fraction of amorphous phase,the equilibrium phases CuZr₂and Cu₁₀Zr₇,austenite,or martensite.Kinetics of CuZr crystallization is studied by performing a range of scan rates from 10 K/s to 21000 K/s using nanocalorimetry that we find the crystallization on heating and on cooling are controlled by growth and nucleation,separately.The heat treatment to obtain CuZr martensitic phase was studied using nanocalorimetry.We explore the conditions for the formation of the martensitic phase responsible for the shape memory properties of this alloy.CuZr martensite can be formed only when the sample is heated to partitaly melted and cooled down to room temperature.Stability of martensitic phase transition is studied by performing fast thermal cycles.Result shows that fast,low-temperature cycling through the martensitic transformation increases the hysteresis,which we attribute to the accumulation of defects during the martensitic transformation.If the austenitic phase is given sufficient time at elevated temperature to annihilate these defects,the transformation is stable under thermal cycling conditions.On the other hand,by using the developed temperature-resistance sensor arrays that is capable to measure the electrical resistance of thin-film materials as a function of temperature and composition,we studied the martensitic transition of Ni-Ti-Cu shape memory alloys and glass forming ability of Pd-Si based metallic glasses.For the latter,we find that the change in resistance on crystallization correlates with glass-forming ability.This observation may be useful in identifying good glass formers using high-throughput techniques.