The wetting behaviors of molten Zr 55 Cu 30 Al 10 Ni 5 metallic glass alloy on polycrystalline a-Al 2 O 3 substrates were investigated using a modified sessile drop method at 1133 to 1193 K in vacuum. Excellent wettability with final contact angles approaching zero degree and mild interfacial reaction were observed. The spreading followed a well-defined exponential decay law. It is the Zr adsorption at the interface and then formation of a Zr-Cu precursor film rather than the interfacial reaction that accounts for the excellent wettability in this system.

Usually gas solubility measurements in metals are done isothermally and separately for the solid and liquid states. The knowledge of gas solubility at phase changes, especially in the melting range, is of a predominant interest e.g. for foundrymen or for welders, as defects (segregation, gas pores, inclusions) may occur due to the change of solubility. Therefore, a method has been developed, in which a finely grained sample is exposed to a temperature gradient in a long ceramic tube, until equilibrium with the gas phase with regard to local temperature is reached in all locations. The chilled sample is subdivided into small samples which can be analysed for gas content. The method is demonstrated for the determination of nitrogen solubility in iron and some iron‐nickel alloys, where results for the austenite and δ‐ferrite phases are presented.

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Wetting of ZrO2–3 mol% Y2O3 substrates by a molten Zr55Cu30Al10Ni5 bulk metallic glass forming alloy was studied using a modified sessile drop method at 1133–1473 K in a high vacuum and their interfacial chemistry was investigated. The time variation in the contact angle shows anomalous temperature dependence at 1133–1293 K, i.e., the initial contact angle gradually decreases while the final contact angle increases with increasing temperature. In the range of 1293–1473 K, the contact angle sharply decreases in the initial stage but shows little change in the subsequent long isothermal duration. A distinct reaction layer consisting of substoichiometric ZrO2−x was developed at the interface. The remarkable temperature dependence of the wettability is due to the competition among the adsorption and accumulation of the active atoms such as Zr at the interface, the interfacial reaction, and the release of oxygen from ZrO2. The adsorption of Zr at the triple junction, particularly enhanced by the structural transition of ZrO2, plays an important role in promoting the wettability. In contrast, the oxygen release leads to the oxidation of the active atoms and ready pinning of the triple line, thus deteriorating the wettability. The interfacial reaction may promote the wetting as well, but its role is limited because on the one hand, it consumes the adsorbed active Zr atoms, and on the other, the pinning of the triple line due to the compositional oxidation considerably weakens its function.