metal phase transformation lab

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Purdue University *

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23500

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Mechanical Engineering

Date

Jan 9, 2024

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pdf

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2

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MSE 235: Thermal Properties of Metals Instructions and Safety: Please read this handout and the background reading before the pre- lab lecture. You will need to wear long pants, close-toed shoes, and safety glasses. The lab will meet in ARMS 2160. Background Reading: Review Sections 9.1-9.8 from “Chapter 9: Phase Diagrams™ in Callister and Rethwisch, Materials Science and Engineering: An Introduction, John Wiley & Sons, Inc. Objectives & Overview: Through this lab activity, students will have a better understanding of the information contained in a phase diagram and the concept of phase transitions and latent heat. To achieve this, students will record temperature measurements of a molten metal alloy as it cools, and will use these temperatures to identify the occurrence of a phase change. Instructions for your lab report are contained at the end of this handout, and a lab report template 1s available on BrightSpace. Please download the lab report template and modify it for your lab report. Submit your lab report through BrightSpace. Before the end of lab, make sure your team has a plan to share all of the data with each other. Materials & Equipment: K-type thermocouples & multimeters; ceramic tube to protect the thermocouple wire; blow torch; five ceramic crucibles; two different types of metal (“A” and “B”); sand casting equipment; furnaces; timer; PPE and other protective equipment specific to the casting lab space. Lab Procedure: 1) With your TA, discuss the safety precautions that are required for working with molten metal. 2) Working as a team, measure five different batches (mixtures) of metal A and metal B, with compositions listed in Table 1. Each batch should weigh approximately 100 g total. Table 1: Alloy batch compositions. Batch ID | Metal A [wt.%] | Metal B [wt.%] Pure A 100 0 91.2 A-B 91.2 8.8 50 A-B 50 50 25 A-B 25 75 Pure B 0 100 3) Put the batches in the crucibles provided and place them into a furnace preheated to > 600°C. 4) Determine how to efficiently and accurately measure the metal temperature as it freezes: who will hold the thermocouple, who will time the measurements, who will record temperature, etc. 5) When the metal is fully molten, remove one of the crucibles from the furnace. 6) As the molten metal cools, measure and record its temperature every 10-15 seconds or as advised by your TA. This data will be used to construct a cooling curve for that batch. 7) Repeat steps 5 & 6 for all five batches of metal. The data you collect (i.e., temperature vs. time) will be used to construct cooling curves for each batch.
Questions to Consider: Did each alloy cool in the same manner or were differences observed between the five alloy compositions? Why do you think this is? Lab Report Requirements & Contents: To prepare your report, a .docx template is available on BrightSpace; you should download and use/edit this document and then submit this document as a PDF through BrightSpace using the appropriate assignment link. The report is worth a total of 65 points. Please note following: all figures and tables should be properly labeled and include a descriptive caption, all reported numerical values have an appropriate number of significant figures, data is analyzed/summarized using appropriate statistical methods, any primary source or database that was consulted should be properly cited and included in the reference list, e keep in mind the attributes of a well-designed, mindful figure that clearly communicates the required information (remember it is good practice to combine relevant data into the same plot), and e written text should be free from spelling and grammar errors, and please keep the elements of technical writing in mind. Abstract (10 pts): In a single paragraph that is less than 150 words, write a short summary of the main finding(s) of the lab report, including any important numerical results. Results (40 pts): o A graph (Fig. 1) of the recorded temperature as a function of time (i.e., cooling curves) for all five batch compositions that were investigated by your lab group. Make sure that the different data series can be easily distinguished from each other and are clearly labeled directly on the graph or in a corresponding legend. (15 pts) o A graph (Fig. 2) of the liquidus line determined from your cooling curve results. Label cach point with the batch composition. (10 pts) e Write a short paragraph (less than 250 words) that summarizes any relevant in-lab observations from the experiments as well as clearly describes the important trends that are present in Fig. 1 and 2. Directly refer to your figures in this paragraph. (15 pts) Discussion (15 pts): Write a series of short paragraphs (less than 350 words total) that answers the following questions. Be sure to properly cite your sources for any scientific information as well as reference values or phase diagrams. 1. What metal is “A” and what metal is “B”? How do you know this? Knowing what A and B are, find a phase diagram for this alloy and include this in your report (Fig. 3). Don’t forget to properly cite the reference/source for the phase diagram that you found. 2. Referring to Fig. 1, explain any interesting/notable features in your cooling curves. Compare the phase diagram (Fig. 3) with your Fig. 2, clearly explaining any similarities or differences. (IS
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