Today's Phase Diagram

So the above diagram is a Binary phase diagram from the Aluminum (Al) - Chromium (Cr) system. Horizontal lines are 3-phase equilibria. Curved lines and vertical lines separate 2-phase fields and 1-phase fields. One-phase fields are all labeled (eg. (Cr), L, Al4Cr, etc.). So basically, for a given composition of alloy (like 60%Cr, 40% Al), you can see what phases are likely to form as you heat the metal from room temperature to a liquid state. With this alloy, it will begin to melt at 1350 C and will finish melting at near 1500 C. Any guesses as to why it melts over 150 C? In other words, why would you have some solid (36%) and some liquid (64%) at 1400 C?

The Answer next week...