EG-M93 Metallurgy and Alloy Design Why should design engineers and metallurgist be worried about segregation, constitutional undercooling and the Hume-Rothery rules? Write a 1000-word essay (excluding references) to discuss the relevance of segregation, constitutional undercooling and the Hume-Rothery rules to mechanical properties of Nickel based alloys. You may also use one or more examples of other non-ferrous alloys to support your discussion. This assignment is worth 25% of the module (25 marks). The criteria for assessing the essay are included at the end of this document. Note that Turnitin will compare your essay with all previously submitted essays and papers available in the literature including internet. Every sentence in this essay must be your own. You need to assume that every academic misconduct case will be reported and dealt as per university regulations'. Format: 11 point, Times New Roman font setting, single column format. Margins: Left, right, top and bottom at least 1.5 cm You must include the word count after the last line of the essay and not exceed the 1000-word limit. Your essay is a story that links the following topics together. See the marking scheme. You are not expected to simply answer the following questions but demonstrate that you understand the knowledge, relate it to the crystal structures of the referenced elements, explain it in your words and provide examples of how insights are applied in practice via research papers. Explain ways in which a eutectic phase resulting from segregation would alter the expected behaviour of the alloy by citing peer reviewed journal papers. Use terms Micro, Macro and Dendritic¹ segregation terms demonstrating your understanding. What is the effect of alloying elements²,³? How do they relate with the partition coefficient 'k'? Explain dendrite fragmentation, its role in the nucleation process and multiplication process and discuss how columnar to equi-axed transition occurs in 1 https://www.phase-trans.msm.cam.ac.uk/2014/segregation.pdf 2 See "Segregation of elements in Nickel based superalloys" paper on Canvas 3 See Segregation behaviour of alloying elements in different oriented single crystal nickel" paper on Canvas Page 1 of 4 castings. Discuss if there is any evidence in journal papers whether segregation, natural convection in the inter-dendritic flow is related to constitutional undercooling Illustrate your understanding of constitutional undercooling and its relevance in developing a planar, cellular to dendritic transition for the solid-liquid interface 5, 6. How does the constitutional undercooling relate to partition coefficients and why the knowledge of partition coefficients for various alloy elements is important in predicting dendritic solidification and subsequent mechanical properties? Include discussion on the effect of primary and secondary dendrite arm spacing and solidification time on mechanical properties with references to published peer reviewed literature. Discuss its relevance to current research papers7,8. Discuss the formation of substitutional and interstitial solid solution and intermetallic compounds with reference to Hume-Rothery rules for solid solutions in binary alloys. Explain the limitations of Hume- Rothery rules when applied to multicomponent and high entropy alloys9,1 O 10 11 12 Use additional references and citations. REFERENCES Use the Vancouver referencing system 13. References should have the following elements: author(s); year of publication; title; and source (i.e., publisher and place of publication in the case of books and reports only). Book titles are underlined; titles of articles are enclosed with double quotation marks; journal titles are underlined. The journal title is followed by the volume number, then the number within the volume (or the month or season, depending upon the journal's style), and then the page numbers. You can use the DOI link. Internet reference: www.swansea.ac.uk Last accessed on 1st October 2010. https://www.researchgate.net/publication/232016000_Segregation_and_grain_refinement_in_cast_titanium _alloys See "Solidification velocity of undercooled Ni-Cu alloys" paper on Canvas 6 See "Seeding of Single-Crystal Superalloys" paper on Canvas 7 https://www.mdpi.com/1996-1944/13/23/5517 https://www.nature.com/articles/s41598-021-82713-3 9 https://link.springer.com/article/10.1007/s11837-015-1594-2 10 https://core.ac.uk/download/pdf/302358579.pdf 11 https://pubs.acs.org/doi/10.1021/jp908415y 12 See "Compositional approach to designing FCC high-entropy alloys" paper on Canvas 13 https://en.wikipedia.org/wiki/Vancouver_system Page 2 of 4 Criteria for assessing the 25% 1000-word essay. Conceptual Clarity Each paragraph has a theme and it conveys an argument. An argument may have two sides. Other authors may have different experience or point of view. This is clearly identified and put together in a logical and easy to understand way. Corroboration with other sources is always done. Only one reference cited at a time and three or more unique and credible references are cited per paragraph. At least one relevant example is given from a peer reviewed paper and is well justified in the text. The language used is clear and grammatically correct and written in student's own words. Schematic diagrams used (either handwritten with image capture or drawn using computer based packages) are easy to read and used to support the discussion. The use of figures is appropriate, properly explained and add significant value to the report. Paragraphs are connected well to develop a logical story. The answer has a structure with introduction on how information is laid out and the purpose of the essay is followed by discussion and conclusion. Instead of discussing different topics separately, discussion focuses on how they connect together to explain a claim/fact/observation found in a research paper. The discussion is written in a way that it is clear to see how it has led to an informed decision leading to the conclusion and recommendations. The question is answered fully. It is clear that the student has listened to the recorded zoom lecture and understood the concepts on power point lecture slides. All information is relevant and necessary to answer the question. Citations are given in the reference section on the following page. Citations and the title text do not contribute towards the 1000-word limit. The 1000- word limit must be met. The total number of words is included at the end of the essay. Depth and Breadth Discussion is scientific and demonstrates conceptual clarity of fundamental metallurgical knowledge. Clear evidence that the student has researched the topic around the question. Concepts are described in student's own words, rather than textbook definitions, with reference to composition at the crystal structure level, relating partition coefficients to constitutional undercooling and segregation. In other words, segregation is described at the crystal structure level and linked with constitutional undercooling, partition coefficient and solid solubility rules with examples from peer reviewed published research papers. Rating All criteria are satisfied and exceeded [13-15] All criteria met and some exceeded [10-12] All criteria met [8-9] Additional work necessary to meet at least one criterion [6-7] Two or more criteria not met [0-5]. All criteria are satisfied and exceeded [8-10] All criteria met and some exceeded [7-8] All criteria met [6-7] Additional work necessary to meet at least one criterion [5-6] Page 3 of 4 Explains the context and experimental conditions used when citing other work. There is qualitative and quantitative discussion on the effect of segregation, constitutive undercooling and solid solubility analysis on improvement/deterioration of properties throughout the text. The authenticity is always cross checked with other sources and if it is not possible uncertainty is quantified suggesting the need of further research. Effect of alloying elements and Interactions is discussed in the context of its impact on properties. Two or more criteria not met [0-5]. https://myuni.swansea.ac.uk/academic-life/academic-regulations/assessment-and-progress/academic- misconduct-procedure/#penalties-available-to-the-committee-of-enquiry-in-cases-of-academic-misconduct-in- non-examination-conditions-is-expanded&to-36-academic-misconduct-in-non-examination-conditions-is- expanded Page 4 of 4