Question 10.7: Compositions of Phases in the Cu-Ni Phase Diagram Determine ......
Compositions of Phases in the Cu-Ni Phase Diagram
Determine the composition of each phase in a Cu-40% Ni alloy at 1300 °C, 1270 °C, 1250 °C, and 1200 °C. (See Figure 10-11.)
The vertical line at 40% Ni represents the overall composition of the alloy.
● 1300 °C: Only liquid is present. The liquid must contain 40% Ni, the overall composition of the alloy.
● 1270 °C: Two phases are present. A horizontal line within the α + L field
is drawn. The endpoint at the liquidus, which is in contact with the liquid region, is at 37% Ni. The endpoint at the solidus, which is in contact with the a region, is at 50% Ni. Therefore, the liquid contains 37% Ni, and the solid contains 50% Ni.
● 1250 °C: Again two phases are present. The tie line drawn at this temperature shows that the liquid contains 32% Ni, and the solid contains 45% Ni.
● 1200 °C: Only solid a is present, so the solid must contain 40% Ni.