Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《中国腐蚀与防护学报》
Abstract: Three high- entropy alloys Co1.5CrFeNi1.5Ti0.5Mo0.1, AlCoCrFeNiSi0.1 and TaNbHfZrTi were prepared by arc melting. Their phase structure, microstructure and chemical composition were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). A commercial alloy 690TT was used as the contrast material. The repassivation kinetics of the three high entropy alloys in high temperature pressurized water was investigated by means of electrochemical test. The results show that Co1.5CrFeNi1.5Ti0.5Mo0.1, AlCoCrFeNiSi0.1 and TaNbHfZrTi high entropy alloys are all composed of single phase. The crystallographic structure of Co1.5CrFeNi1.5Ti0.5Mo0.1 alloy is fcc, while that of the alloys AlCoCrFeNiSi0.1 and TaNbHfZrTi is bcc. The SEM results show that the Co1.5CrFeNi1.5Ti0.5Mo0.1 alloy showed a typical dendritic microstructure, of which the dendrite riches in Cr and Fe, but the interdendrite zone riches in Ti and Ni. There is no obvious element segregation observed in the AlCoCrFeNiSi0.1 alloy. The TaNbHfZrTi alloy also exhibited a dendritic microstucture, of which the dendrite riches in Ta and Nb, and the interdendrite zone riches in Hf, Zr and Ti. The repassivation rates of these four alloys in high-temperature pressurized water may be ranked as the following sequence: TaNbHfZrTi>Co1.5CrFeNi1.5Ti0.5Mo0.1>690TT>AlCoCrFeNiSi0.1.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract: Cold galvanizing coatings were prepared. The coating properties were characterized by salt spray test and electrochemical impedance spectroscopy. Among others, the coating with 95.2% (mass fraction) Zn exhibits the highest corrosion resistance to salt spray, and its corrosion product consists of ZnO and Zn(OH)2. When the Zn content is less than 75%, the impedance of coatings in the solution of 3%(mass fraction) NaCl decreases with the increasing immersion time, and thus the coatings provide inferior protectiveness; when the Zn content is greater than 75%, the impedance of the coating decreases firstly and then increases with the increasing time, which may be ascribed to that the Zn powder in the coating acts as sacrificial anode,which was preferentially corroded in the initial statge.