In this paper, glass transition and thermal stability of the Zr-AI-Cu-Ni metallic glasses were investigated by using electrical resistance measurement (ERM), DSC and X-ray diffraction techniques. The experimental results show that the ERM is capable of detecting the glass transition of the amorphous alloys and can help to distinguish the crystallization products of the Zr-AI-Cu-Ni metallic glasses owing to the difference of the electrical resistivity between the precipitation phases.
Yaping WANG and Ke LUState Key Laboratory for RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
The coating process of TiH2 particles with SiO2 layers, and the effect of the coating layer on hydrogen release characteristic of TiH2 powders were studied experimentally. The gelation rate of silicic acid is an important factor for controlling the surface morphologies of coating layers. When the concentration of SiO2-3 is about 0.5 mol/L, the condensation rate of silicic acid is appropriate for the formation of a homogeneous and dense coating membrane. The results of hydrogen release at 700 ℃ show that TiH2 particles coated with silicon dioxide layers can efficiently delay the starting time of hydrogen release of TiH2 powders to 60100 s.
CuCr25 alloys containing different Ni content were prepared by vacuum induction melting (VIM). The micro structure and properties were tested. The results show that with the increase of Ni content in CuCr25 alloys, the Cr phase changed from developed dendrite into nodular grains and was drastically refined; the electrical conductivity significantly decrease, but still reach the level of conventional CuCr50 when the Ni content is below 0.5%. The Ni content had little influence on their breakdown strength. The first breakdown sites transferred to the boundary of Cu and Cr phase for CuCr25Ni compared to the Cr phase for CuCr25 without Ni.
