Devices may be in contact with molten metals such as copper, for example. The devices may include, but are not limited to, a die used for producing articles made from the molten metal, a sensor for determining an amount of a dissolved gas in the molten metal, or an ultrasonic device for reducing gas content (e.g., hydrogen) in the molten metal. Niobium may be used as a protective barrier for the devices when they are exposed to the molten metals.