MSE45_HW6_2022

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MSE 45: Properties of Materials Fall 2022 Homework 6 Instructor: Matthew P. Sherburne Answer the following questions and provide as many details and as much work as possible to assure partial credit. Recall that homeworks may be completed in groups of two students or you may choose to work independently, but all students must turn in an individual homework. You must indicate your homework partner (if any); see the Syllabus for full details. Homeworks must be submitted in .pdf format and submitted online via bCourses . Graphs should be completed in a graphing software program. 1. (16 pts.) Cite the phases that are present and the phase compositions for the following alloys: a. (4 pts.) 15 wt% Sn–85 wt% Pb at 100°C (212°F) (figure from Callister) b. (4 pts.) 85 wt% Ag–15 wt% Cu at 800°C (1470°F) (figure from Callister)

MSE 45: Properties of Materials Fall 2022 Homework 6 Instructor: Matthew P. Sherburne c. (4 pts.) 1.25 kg Sn and 14 kg Pb at 200°C (390°F) (Fig. 9.8; pg. 315) (figure from Callister) d. (4 pts.) 21.7 mol Mg and 35.4 mol Pb at 350°C (660°F) (Fig. 9.20; pg. 327) (figure from Callister)

MSE 45: Properties of Materials Fall 2022 Homework 6 Instructor: Matthew P. Sherburne 2. (20 pts.) Determine the relative amounts (in terms of mass fractions) of the phases for the alloys and temperatures given in Problem 1. a. (5 pts.) For an alloy composed of 15 wt% Sn-85 wt% Pb and at 100°C. b. (5 pts.) For an alloy composed of 85 wt% Ag-15 wt% Cu and at 800°C. c. (5 pts.) For an alloy composed of 1.25 kg Sn and 14 kg Pb (8.2 wt% Sn-91.8 wt% Pb) and at 200°C. d. (5 pts.) For an alloy composed of 21.7 mol Mg and 35.4 mol Pb (93 wt% Pb-7 wt% Mg) and at 350°C. 3. (20 pts.) For a 76 wt% Pb–24 wt% Mg alloy (figure from Callister), make schematic sketches of the microstructure that would be observed for conditions of very slow cooling at the following temperatures: 575°C, 500°C, 450°C, and 300°C

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MSE 45: Properties of Materials Fall 2022 Homework 6 Instructor: Matthew P. Sherburne 4. (14 pts.) The figure below is the tin–gold phase diagram (also figure in textbook), for which only single-phase regions are labeled. Specify temperature–composition points at which all eutectics, eutectoids, peritectics, and congruent phase transformations occur. Also, for each, write the reaction upon cooling.

MSE 45: Properties of Materials Fall 2022 Homework 6 Instructor: Matthew P. Sherburne 5. (13 pts.) Consider 6.0 kg of an austenite containing 0.45 wt% C (figure from Callister) that is cooled to a temperature just below 727°C. a. (1 pts.) What is the proeutectoid phase? b. (4 pts.) How many kilograms each of total ferrite and cementite form? c. (4 pts.) How many kilograms each of pearlite and the proeutectoid phase form? d. (4 pts.) Schematically sketch and label the resulting microstructure.

MSE 45: Properties of Materials Fall 2022 Homework 6 Instructor: Matthew P. Sherburne 6. (8 pts.) Steels e. (4 pts.) What is the distinction between hypoeutectoid and hypereutectoid steels? f. (4 pts.) In a hypoeutectoid steel, both eutectoid and proeutectoid ferrite exist. Explain the difference between them. What will be the carbon concentration in each? 7. (9 pts.) In the figure below is the pressure–temperature phase diagram for H2O. Apply the Gibbs phase rule at points A, B, and C; that is, specify the number of degrees of freedom (or the number of externally controllable variables that need be specified to completely define the system) at each point. Clearly define all variable and the values for each variable.

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