C₀ = Σ(mᵢ Cᵢ)/ΣmᵢC₀: average composition; mᵢ: masses; Cᵢ: compositions on the same basis.
Use when: Mixture balance before losses or reactions.
Copper–nickel alloy formation
Link composition, fusion and solidification of an alloy.
What is happening?
An alloy combines several elements in a metallic material. The Cu–Ni system is a classic example of extended solid solubility; its solidification is described with liquid, solid and two-phase domains.
In a domain with two phases at equilibrium, the composition of each phase generally differs from the average composition. The lever rule relates these compositions to the fractions of the phases.
The formulas, with their conditions.
fα = (Cβ − C₀)/(Cβ − Cα)fα: phase fraction α; Cα, Cβ: compositions at the ends of the bond line.
Use when: Two-phase equilibrium, C₀ between Cα and Cβ and basis of coherent composition.
Where is this principle used?
Alloy foundry
Develop a composition and monitor its solidification.
Manufacturing of Cu–Ni components
Choose the properties of a material according to its application.
What to observe in the experiment
Mix two charges of known compositions, calculate C₀ then follow the two-phase zone during cooling.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian