A High Throughput Study On Corrosion Properties Of Transition Metals And Oxides

Transition metals have various physical and chemical properties due to their unique valence electron structure,among which the shape memory effect is a special physical property,which has been widely studied in recent years.Among many transition metalbased shape memory alloys,Ti-Ni-Zr alloy attracts attention from the research society due to their high martensite transition temperature,wide temperature response range,shape memory effect,and strong hyperelastic strain.In recent years,the rapid development in the fields of microsensors,micro aircraft,and artificial biomaterials requires an increasing demand for shape memory alloys applications.Therefore,it is critical to developing new materials with high corrosion resistance and low power response for the extreme environment,such as high salt or high humidity,application scenarios.However,the majority of corrosion resistance researches are aiming at mono or binary material system.The study on ternary or above material system requires labors exponentially higher than the mono or binary system,resulting in fewer achievements with less systematicness.High-throughput experiment is an advanced material research technology,which can greatly accelerate the material development process.High-throughput experiment consists of two parts: high-throughput preparation and high-throughput characterization.At the former stage,multi-component materials are regularly integrated into a system to produce the combinatorial thin film library.The latter utilizes continuous scanning or multi-channel parallel testing method to achieve complete information of the combinatorial thin film library.In this paper,Ti-Ni-Zr alloy is studied based on the high-throughput experimental method.The main research content includes the following aspects:1.Development of a set of Ti-Ni-Zr combinatorial thin film library preparation process based on magnetron sputtering preparation process.This includes parameters during the sputtering process and heat treatment process.In order to solve the problem caused by the contamination of the adjacent sample unit,a lithographic mask is introduced combining with a physical mask of the baffle plate to maintain the independence of each sample unit.324 sample units can be separated by 0.268 mm.2.A non-electrochemical method,which combines the change of the resistance and the morphology analysis,is proposed to evaluate the corrosion resistance of the alloy.The accuracy and reliability of such a method are verified by comparing it with the electrochemical test.3.Ti-Ni-Zr combinatorial thin film library is prepared based on the improved highthroughput synthesis process.The corrosion mechanism of the alloy is systematically investigated.The correlation between alloy composition,structural evolution,and corrosion resistance is studied.The Ti-Ni-Zr alloy with the best corrosion resistance performance is screened out.The result shows that the best corrosion resistance can be achieved for a stoichiometry of Ti(10-95 at.%),Ni(90-5 at.%),Zr(< 25 at.%)under 700 ℃ heat-treatment process.4.The influence of different phase forming temperatures on the crystal structure and corrosion resistance of Ti-Ni-Zr alloy is studied.The results indicate that higher heat treatment temperature is beneficial to the grain refinement of the alloy system,resulting in compact surface passivation film and therefore improve its corrosion resistance.