Phase relationship in the ternary Al-CoW system was established for the whole composition range at 600 o C by X-ray powder diffraction, scanning electron microscopy and energy dispersive spectroscopy. Isothermal section of this system comprises of 15 three phase and 28 two phase regions. Except the L12-γ′ phase, a new ternary phase T has been found. The average composition of the T phase is 22.6 at.% Al, 67.0 at.% Co and W in balance. The solubility of W in AlCo is 3.0 at%, the solubility of Al in Co3W and Co7W6 is both 3.1 at%, and the solubility of Co in Al4W reaches 3.6 at.%. Solubility of the third component in the other binary phases is limited. The present work is essential to develop a thermodynamic database for developing Co-related hightemperature alloys.
Phase equilibria of the Al-Si-Zr system were investigated using equilibrated alloys. All alloys were studied by X-ray powder diffraction, scanning electron microscopy and energy dispersive spectroscopy. The ternary phase τ1 was found at 700 and 900 o C, while the τ2 phase was only identified at 900 o C. 12 three-phase regions were experimentally determined in isothermal sections of the Al-Si-Zr system at both 700 and 900 o C. The solubility of Si in the intermediate and solution phases (i.e. Al3Zr, Al2Zr, Al3Zr2, AlZr3, α-Al and (Zr)) at the Al-Zr side is limited, whereas the solubility of Al in the Si-Zr intermetallic (except the Si2Zr3 phase) is reverse. In addition, Al in the αSiZr phase at 900 o C decreased to 0.5 at.% from 10.3 at.% at 700 o C.
Reactions of Co 2 Si alloy with liquid zinc for annealing time up to 720 minutes were studied by means of scanning electron microscope, energy-dispersive X-ray spectroscope and electron backscattered diffraction techniques. The results showed that periodic patterns, Co 2 Si / (γ 2 + η-Zn), were observed in the reaction zone, and its thickness and morphology were dependent on the crystallographic orientation of Co 2 Si grain. The relationship between anisotropy growth of the periodic patterns and crystal structure was explained with the concept of dangling bonds. The thermodynamic foundation and mechanism of formation of the periodic layered structure were elaborated in this paper.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.