Lab 14 report: Solidification of Pb-Sn Alloys PDF

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Solidification of Pb-Sn Alloys...

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Solidification of Pb-Sn Alloys

By

Quang Nguyen

School of Engineering Grand Valley State University

Laboratory Module 14 EGR 250 – Material Science & Engineering Section 902

Instructor: Professor Lindsay Corneal

October 20, 2016

1. Abstract The main learning objectives of the experiment were to reinforce the basic principle of solidification, to determine alloy composition based on solidification cooling curve and equilibrium phase diagrams, to interpret phase diagram, and to apply Lever rule. In this laboratory activity, the cooling curve and a Pb-Sn phase diagram were utilized to identify the composition and characteristic temperature of two unknown alloys. Moreover, Lever rule was applied to calculate the amount of different phases in the experimental alloys during solidification. By interpreting the cooling curve and a Pb-Sn phase diagram, alloy A was determined to be hypoeutectic alloy with solidification rate of 0.055, while alloy D was determine to be hypereutectic alloy with solidification rate of 0.217. Moreover, the amount of eutectic at room temperature in alloy A is 60.6%, while amount of eutectic at room temperature in alloy D is 0%. The type of primary phase in each sample was identified as α phase in sample A and β phase in sample D.

2. Results

After interpreting the solidification curve of sample A and sample D, which was shown in Figure 1, the composition and characteristic temperature as well as the amount of different phases in the experimental alloys were determined.

Figure 1: Heating and Cooling Curve of Sample A and Sample D

Two black lines were drawn followed the slope of each cooling curve to identify the deflection point in each curve, that showed the liquidus temperature as well as the elapsed time at liquidus temperature of each samples. According to the cooling curve, the eutectic temperature and solidus temperature was determine as 181℃ for both samples A and D. The elapsed time at solidus temperature was determined as the time for each sample to reach the solidus temperature. With the elapsed time and temperature, the solidification rates of two specimen were calculated as 0.055 for sample A and 0.217 for sample D. Also, the initial melting temperature of each sample was determined, which was the highest point of each graph. The initial temperature of sample A was 328℃, and the initial temperature of sample D was 329.4℃.

Figure 2: Pb-Sn phase diagram

According to the Pb-Sn phase diagram, the composition as well as the type of each alloy could be identified. Alloy A was hypoeutectic with 45% weight of Sn and 55% weight of Pb, while alloy D was hypereutectic with 100% weight of Sn. The primary phase of alloy A was 𝛼 , and the primary phase of alloy D was 𝛽 . In addition, the amount of eutectic, primary phase, 𝛼 phase, and 𝛽 phase were calculated. The experimental result was shown in experimental result sheets in Figure 3. Furthermore, the microstructures sheet of alloy A and alloy D at 330℃, which was the initial melt temperature, in mushy region, and at room temperature were drawn and shown in Figure 4.

Figure 3: Experimental Result Sheet

Figure 4: Microstructure Sheet

3. Conclusion 1. The laboratory successfully reinforced the basic principle of solidification by strengthen the phase diagram interpretation skills and application of Lever rule 2. Alloy A that contains 60.6% of eutectic at room temperature is hypoeutectic alloy with 0.055 solidification rate, while alloy D that does not contain eutectic at room temperature is hypereutectic alloy with 0.217 solidification rate. 3. Type of primary phase in alloy A is 𝛼 , while type of primary phase in alloy D is 𝛽...