Example Questions Midterm 2 343

Q1 Phase Diagrams

(i) Determine the compositions and temperature of the three-phase invariant reactions and name the type of reaction. (ii) A 1% carbon steel is cooled slowly from the melt to room temperature. Sketch the expected microstructure and name the phases. (iii)Describe two hardening mechanisms in steels.

Q2 Phase Diagrams

(i)

The Pb-Sn phase diagram is shown in the figure. What is the solubility limit of Pb in Sn and of Sn-Pb?

(ii)

What is the eutectic composition?

(iii)

A mixture of 60% Pb is melted and the cooled slowly. What is the composition and amount of all phases at 550°, 500° and 450° K?

(iv)

Sketch the microstructure of this alloy at room temperature.

Q3 Creep

Calculate time to failure for an Equiaxed MAR-M 247 MFB alloy at 210 MPA and 8000 C.