Thermodynamics-based design of creep resistant Mg solid solutions using the Miedema scheme

Miedema’s coordinates are used to rank 4 model bina ry alloys considering the respective values of enthalpy of formation and the tendency to developin g short range order (SRO) and intermetallic compounds. The terminal solid solubility generally increases whereas the tendency to order decreases with decreasing heat of formation, and ha r ening by near-random solid solution and precipitation is expected to be dominant for solute s with low tendency to order, such as Al. For solutes with an intermediate tendency to order, suc h as Zn, or to form compounds, such as Gd, SRO is predicted to dominate the hardening. For solutes , whose very large heat of formation leads to very high melting point intermetallics forming straight from the liquid, such as Sb, the terminal solid solubility is too low for any solute based hardenin g to be feasible. Implications for alloy design and selection regarding precipitation hardening and cre ep r sistance are discussed.