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Effects of Al and Mo on high temperature oxidation behavior of refractory high entropy alloys

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Transactions of Nonferrous metals Society of China 2019年第7期29卷 1476-1483页

作者： Yuan-kui CAO Yong LIU Bin LIU Wei-dong ZHANG Jia-wen WANG Meng DU State Key Laboratory of Powder metallurgy Central South UniversityChangsha 410083China

refractory high entropy alloys have superior mechanical properties at high temperatures, and the oxidation behavior of these alloys is very important. The present work investigated the high temperature oxidation behavior of three alloys with compositions of TiNbTa0.5Zr, TiNbTa0.5ZrAl and TiNbTa0.5ZrAlMo0.5, and the effects of alloying elements were discussed. Results indicated that the oxidation rates of the TiNbTa0.5Zr and TiNbTa0.5ZrAl alloys are controlled by diffusion, and obey the exponential rule. However, the oxidation rate of the TiNbTa0.5ZrAlMo0.5 alloy is controlled by interface reaction, and obeys the linear rule. The addition of Al leads to a better oxidation resistance by forming a protective oxide scale. However, the protection of Al-rich scale is weakened by the addition of Mo. Extensive pores and cracks occur in the oxide scale of the TiNbTa0.5ZrAlMo0.5 alloy, resulting in a significant decrease in oxidation resistance.

关键词： high entropy alloy refractory metal high temperature oxidation oxide scale microstructure

Effect of Ni content in Cu_(1-x)Ni_(x) coating on microstructure evolution and mechanical properties of W/Mo joint via low-temperature diffusion bonding

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Journal of Materials Science & Technology 2020年第19期54卷 171-180页

作者： Mei Rao Guoqiang Luo Jian Zhang Yiyu Wang Qiang Shen Lianmeng Zhang State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN37831-6064USA

The 93 W and Mo1 refractory metals were bonded with different Cu_(1-x)Ni_(x) coating interlayers of various Ni content using plasma-activated sintering at 700℃.The effects of the Ni content in the Cu_(1-x)Ni_(x) coating interlayer on the interfacial microstructure evolution and mechanical properties of the W/Mo joints were *** maximum average shear strength of the W/Mo joint was 316.5 MPa when the Ni content of the Cu_(1-x)Ni_(x) coating interlayer was 25%.When the Ni content of the Cu_(1-x)Ni_(x) coating interlayer was below 50%,the atomic diffusion at the W/Mo joint interface was adequate without the formation of intermetallic compounds,as demonstrated by the High Resolution Transmission Electron Microscope analyses of the *** presence of Ni in Cu_(1-x)Ni_(x) promoted diffusion bonding at the interface,which contributed to the high mechanical properties of the W/Mo *** an increase in the Ni content of the Cu_(1-x)Ni_(x) coating interlayer,the Mo Ni intermetallic compound(IMC)nucleated and grew at the Cu1-xNix coating/Mo1 *** the Ni content of the Cu_(1-x)Ni_(x) coating interlayer was above 50%,the generation of a brittle Mo Ni IMC weakened the shear strength of the W/Mo joint dramatically.

关键词： refractory metal Cu_(1-x)Ni_(x)coating interlayer Solid solution MoNi IMC Microstructure Shear strength

Effects of Tungsten and Boron Contents on Crystallization Temperature and Microhardness of Tungsten Based metallic Glasses

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Acta metallurgica Sinica(English Letters) 2015年第6期28卷 733-738页

作者： Pelin ztürk Aytekin Hitit Department of Materials Science and Engineering AfyonKocatepe University

Effects of tungsten and boron contents on the thermal properties and microhardness of W-Fe-B metallic glass system were studied. Thin foils, with thicknesses of 20 and 100 ktm, of the alloys were produced by piston and anvil method in an arc furnace. The structures of the foils were investigated by X-ray diffraction. Thermal stabilities of the alloys were examined by using differential scanning calorimetry. 20-μm- thick foils of all the alloys were determined to be fully amorphous, but crystalline phases were detected in the 100-μm-thick foils. It was found that crystallization temperatures of the alloys are between 1060 and 1177 K. Tungsten and boron content increases improve the crystallization temperature and microhardness of the alloys significantly, but deteriorate the glass forming ability of the alloys. It was also observed that for constant Fe content, increasing tungsten content to the level higher than that of boron content does not result in any further improvement in crystallization temperature, but improves glass forming ability significantly. The alloy containing highest total amount of tungsten and boron, W35Fe35B3o, has the highest crystallization temperature, 1177 K, and microhardness, 1634 HV.

关键词： metallic glass refractory metal Crystallization temperature Hardness