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Scandium metal processing for aerospace application / Sephira Riva

Swansea University Author: Sephira Riva

DOI (Published version): 10.23889/SUthesis.39867

Abstract

The use of scandium has been conventionally restricted to minor additions in alloys for structural applications. The term ‘scandium effect’ came thus to indicate the properties improvements caused by the precipitation of scandium intermetallics in the matrix.The development of High-Entropy Alloys (HE...

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Published: 2018
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa39867
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last_indexed 2020-09-02T03:03:30Z
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2020-09-01T16:49:37.1085231</datestamp><bib-version>v2</bib-version><id>39867</id><entry>2018-05-02</entry><title>Scandium metal processing for aerospace application</title><swanseaauthors><author><sid>6dcef5272de9666e131a555be5da268f</sid><ORCID>0000-0002-8733-5123</ORCID><firstname>Sephira</firstname><surname>Riva</surname><name>Sephira Riva</name><active>true</active><ethesisStudent>true</ethesisStudent></author></swanseaauthors><date>2018-05-02</date><abstract>The use of scandium has been conventionally restricted to minor additions in alloys for structural applications. The term &#x2018;scandium e&#xFB00;ect&#x2019; came thus to indicate the properties improvements caused by the precipitation of scandium intermetallics in the matrix.The development of High-Entropy Alloys (HEA, multi-principal component alloys combining compositional complexity with simple crystal structures) opened the door for the development of new systems, and therefore for new applications for lightweight metals such as scandium.This work is a thorough investigation of the potential of scandium-based in- termetallics in the growing field of HEAs.The synthesis and characterisation of multi-principal component alloys contain- ing scandium as active alloying element illustrate the compound-forming ability of this element. The high mixing entropy of the studied systems (comprising alloys of scandium with first raw metals or with hcp-structured elements) cannot e&#xFB03;ciently inhibit the precipitation of stable intermetallic compounds. Among them, of in- terest is the so-called W -phase, so-far only reported for Al-basedCu-containing commercial alloys.Small scandium additions to Al2CoCrFeNi, Al0.5CoCrCuFeNi and AlCoCr- Cu0.5FeNi cause the segregation of a secondary phase along grain boundaries. This hexagonal Laves phase, formed by scandium in combination with Al, Co, Cr, Cu, Fe and Ni, does not disrupt the HEA matrix and is extremely stable. Moreover, it deeply a&#xFB00;ects microstructure and mechanical properties &#x2013; for ex-ample, by enhancing the HEA stability with the postponement of a T-dependent phase exsolution by roughly 150 &#xB0;C. Furthermore, a synergistic e&#xFB00;ect in the main phase stabilisation takes place when the Sc-doped sample is pressed at 9.5 GPa: no transition occurs and the intermetallic dissolves in the matrix.Preliminary investigations performed by spark-plasma sintering of di&#xFB00;erent additives (among which Sc2O3, used as a source of scandium metal) in combination with the Al CoCrFeNi alloy led to the discovery of a promising nanodiamond HEA composite.</abstract><type>E-Thesis</type><journal/><publisher/><keywords>Scandium, Metallurgy, High-Entropy Alloys, HEA Composites</keywords><publishedDay>31</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2018</publishedYear><publishedDate>2018-12-31</publishedDate><doi>10.23889/SUthesis.39867</doi><url/><notes/><college>COLLEGE NANME</college><department>Engineering</department><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><degreesponsorsfunders>European Space Agency (contract number 4000111643/NL/PA) and National Research Network of Wales (Ser Cymru project NRN046).</degreesponsorsfunders><apcterm/><funders>EGR0682-100</funders><lastEdited>2020-09-01T16:49:37.1085231</lastEdited><Created>2018-05-02T12:16:16.2858614</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Uncategorised</level></path><authors><author><firstname>Sephira</firstname><surname>Riva</surname><orcid>0000-0002-8733-5123</orcid><order>1</order></author></authors><documents><document><filename>0039867-02052018122103.pdf</filename><originalFilename>Riva_Sephira_PhD_2018.pdf</originalFilename><uploaded>2018-05-02T12:21:03.8330000</uploaded><type>Output</type><contentLength>252216812</contentLength><contentType>application/pdf</contentType><version>E-Thesis &#x2013; open access</version><cronfaStatus>true</cronfaStatus><embargoDate>2019-05-01T00:00:00.0000000</embargoDate><copyrightCorrect>true</copyrightCorrect></document></documents><OutputDurs/></rfc1807>
spelling 2020-09-01T16:49:37.1085231 v2 39867 2018-05-02 Scandium metal processing for aerospace application 6dcef5272de9666e131a555be5da268f 0000-0002-8733-5123 Sephira Riva Sephira Riva true true 2018-05-02 The use of scandium has been conventionally restricted to minor additions in alloys for structural applications. The term ‘scandium effect’ came thus to indicate the properties improvements caused by the precipitation of scandium intermetallics in the matrix.The development of High-Entropy Alloys (HEA, multi-principal component alloys combining compositional complexity with simple crystal structures) opened the door for the development of new systems, and therefore for new applications for lightweight metals such as scandium.This work is a thorough investigation of the potential of scandium-based in- termetallics in the growing field of HEAs.The synthesis and characterisation of multi-principal component alloys contain- ing scandium as active alloying element illustrate the compound-forming ability of this element. The high mixing entropy of the studied systems (comprising alloys of scandium with first raw metals or with hcp-structured elements) cannot efficiently inhibit the precipitation of stable intermetallic compounds. Among them, of in- terest is the so-called W -phase, so-far only reported for Al-basedCu-containing commercial alloys.Small scandium additions to Al2CoCrFeNi, Al0.5CoCrCuFeNi and AlCoCr- Cu0.5FeNi cause the segregation of a secondary phase along grain boundaries. This hexagonal Laves phase, formed by scandium in combination with Al, Co, Cr, Cu, Fe and Ni, does not disrupt the HEA matrix and is extremely stable. Moreover, it deeply affects microstructure and mechanical properties – for ex-ample, by enhancing the HEA stability with the postponement of a T-dependent phase exsolution by roughly 150 °C. Furthermore, a synergistic effect in the main phase stabilisation takes place when the Sc-doped sample is pressed at 9.5 GPa: no transition occurs and the intermetallic dissolves in the matrix.Preliminary investigations performed by spark-plasma sintering of different additives (among which Sc2O3, used as a source of scandium metal) in combination with the Al CoCrFeNi alloy led to the discovery of a promising nanodiamond HEA composite. E-Thesis Scandium, Metallurgy, High-Entropy Alloys, HEA Composites 31 12 2018 2018-12-31 10.23889/SUthesis.39867 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D European Space Agency (contract number 4000111643/NL/PA) and National Research Network of Wales (Ser Cymru project NRN046). EGR0682-100 2020-09-01T16:49:37.1085231 2018-05-02T12:16:16.2858614 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Sephira Riva 0000-0002-8733-5123 1 0039867-02052018122103.pdf Riva_Sephira_PhD_2018.pdf 2018-05-02T12:21:03.8330000 Output 252216812 application/pdf E-Thesis – open access true 2019-05-01T00:00:00.0000000 true
title Scandium metal processing for aerospace application
spellingShingle Scandium metal processing for aerospace application
Sephira Riva
title_short Scandium metal processing for aerospace application
title_full Scandium metal processing for aerospace application
title_fullStr Scandium metal processing for aerospace application
title_full_unstemmed Scandium metal processing for aerospace application
title_sort Scandium metal processing for aerospace application
author_id_str_mv 6dcef5272de9666e131a555be5da268f
author_id_fullname_str_mv 6dcef5272de9666e131a555be5da268f_***_Sephira Riva
author Sephira Riva
author2 Sephira Riva
format E-Thesis
publishDate 2018
institution Swansea University
doi_str_mv 10.23889/SUthesis.39867
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
active_str 0
description The use of scandium has been conventionally restricted to minor additions in alloys for structural applications. The term ‘scandium effect’ came thus to indicate the properties improvements caused by the precipitation of scandium intermetallics in the matrix.The development of High-Entropy Alloys (HEA, multi-principal component alloys combining compositional complexity with simple crystal structures) opened the door for the development of new systems, and therefore for new applications for lightweight metals such as scandium.This work is a thorough investigation of the potential of scandium-based in- termetallics in the growing field of HEAs.The synthesis and characterisation of multi-principal component alloys contain- ing scandium as active alloying element illustrate the compound-forming ability of this element. The high mixing entropy of the studied systems (comprising alloys of scandium with first raw metals or with hcp-structured elements) cannot efficiently inhibit the precipitation of stable intermetallic compounds. Among them, of in- terest is the so-called W -phase, so-far only reported for Al-basedCu-containing commercial alloys.Small scandium additions to Al2CoCrFeNi, Al0.5CoCrCuFeNi and AlCoCr- Cu0.5FeNi cause the segregation of a secondary phase along grain boundaries. This hexagonal Laves phase, formed by scandium in combination with Al, Co, Cr, Cu, Fe and Ni, does not disrupt the HEA matrix and is extremely stable. Moreover, it deeply affects microstructure and mechanical properties – for ex-ample, by enhancing the HEA stability with the postponement of a T-dependent phase exsolution by roughly 150 °C. Furthermore, a synergistic effect in the main phase stabilisation takes place when the Sc-doped sample is pressed at 9.5 GPa: no transition occurs and the intermetallic dissolves in the matrix.Preliminary investigations performed by spark-plasma sintering of different additives (among which Sc2O3, used as a source of scandium metal) in combination with the Al CoCrFeNi alloy led to the discovery of a promising nanodiamond HEA composite.
published_date 2018-12-31T03:50:41Z
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score 11.01297

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