On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated Alloy
In this work, the refractory complex concentrated alloy (RCCA) 3.5Al–4Cr–6Ge–1Hf–5Mo–36Nb–22Si–1.5Sn–20Ti–1W (at.%) was studied in the as cast and heat treated conditions (100 h or 200 h at 1500 °C). There was strong macrosegregation of Si in the 0.6 kg button/ingot of the cast alloy, in which A2 so...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-03-01
|
| Series: | Alloys |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2674-063X/3/1/5 |
| _version_ | 1797242331845361664 |
|---|---|
| author | Nik Tankov Claire Utton Panos Tsakiropoulos |
| author_facet | Nik Tankov Claire Utton Panos Tsakiropoulos |
| author_sort | Nik Tankov |
| collection | DOAJ |
| description | In this work, the refractory complex concentrated alloy (RCCA) 3.5Al–4Cr–6Ge–1Hf–5Mo–36Nb–22Si–1.5Sn–20Ti–1W (at.%) was studied in the as cast and heat treated conditions (100 h or 200 h at 1500 °C). There was strong macrosegregation of Si in the 0.6 kg button/ingot of the cast alloy, in which A2 solid solution, D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub>, C14-NbCr<sub>2</sub> Laves phase and Ti<sub>ss</sub> and a ternary eutectic of the A2, D8<sub>m</sub> and C14 phases were formed. The partitioning of Ti in the as cast and heat treated microstructure and its relationships with other solutes was shown to be important for the properties of the A2 solid solution and the D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub>, which were the stable phases at 1500 °C. The near surface microstructure of the alloy was contaminated with oxygen after heat treatment under flowing Ar. For the aforementioned phases, it was shown, for the first time, that there are relationships between solutes, between solutes and the parameters VEC, Δχ and δ, between the said parameters, and between parameters and phase properties. For the contaminated with oxygen solid solution and silicide, trends in relationships between solutes, between solutes and oxygen content and between the aforementioned parameters and oxygen content also were shown for the first time. The nano-hardness and Young’s modulus of the A2 solid solution and the D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub> of the as cast and heat-treated alloy were measured using nanoindentation. Changes of nano-hardness and Young’s modulus of the A2 solid solution and D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub> per solute addition for this multiphase RCCA were discussed. The nano-hardness and Young’s modulus of the solid solution and the βNb<sub>5</sub>Si<sub>3</sub>, respectively, were 9.5 ± 0.2 GPa and 177.4 ± 5.5 GPa, and 17.55 ± 0.5 GPa and 250.27 ± 6.3 GPa after 200 h at 1500 °C. The aforementioned relationships and properties of the two phases demonstrated the importance of synergy and entanglement of solutes, parameters and phases in the microstructure and properties of the RCCA. Implications of synergy and entanglement for the design of metallic ultra-high temperature materials were emphasised. |
| first_indexed | 2024-04-24T18:37:32Z |
| format | Article |
| id | doaj.art-3e0803a3e2f74ec2b80dcdc0be0c3f7b |
| institution | Directory Open Access Journal |
| issn | 2674-063X |
| language | English |
| last_indexed | 2024-04-24T18:37:32Z |
| publishDate | 2024-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Alloys |
| spelling | doaj.art-3e0803a3e2f74ec2b80dcdc0be0c3f7b2024-03-27T13:17:29ZengMDPI AGAlloys2674-063X2024-03-0131599510.3390/alloys3010005On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated AlloyNik Tankov0Claire Utton1Panos Tsakiropoulos2Department of Materials Science and Engineering, Sir Robert Hadfield Building, The University of Sheffield, Mappin Street, Sheffield S1 3JD, UKDepartment of Materials Science and Engineering, Sir Robert Hadfield Building, The University of Sheffield, Mappin Street, Sheffield S1 3JD, UKDepartment of Materials Science and Engineering, Sir Robert Hadfield Building, The University of Sheffield, Mappin Street, Sheffield S1 3JD, UKIn this work, the refractory complex concentrated alloy (RCCA) 3.5Al–4Cr–6Ge–1Hf–5Mo–36Nb–22Si–1.5Sn–20Ti–1W (at.%) was studied in the as cast and heat treated conditions (100 h or 200 h at 1500 °C). There was strong macrosegregation of Si in the 0.6 kg button/ingot of the cast alloy, in which A2 solid solution, D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub>, C14-NbCr<sub>2</sub> Laves phase and Ti<sub>ss</sub> and a ternary eutectic of the A2, D8<sub>m</sub> and C14 phases were formed. The partitioning of Ti in the as cast and heat treated microstructure and its relationships with other solutes was shown to be important for the properties of the A2 solid solution and the D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub>, which were the stable phases at 1500 °C. The near surface microstructure of the alloy was contaminated with oxygen after heat treatment under flowing Ar. For the aforementioned phases, it was shown, for the first time, that there are relationships between solutes, between solutes and the parameters VEC, Δχ and δ, between the said parameters, and between parameters and phase properties. For the contaminated with oxygen solid solution and silicide, trends in relationships between solutes, between solutes and oxygen content and between the aforementioned parameters and oxygen content also were shown for the first time. The nano-hardness and Young’s modulus of the A2 solid solution and the D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub> of the as cast and heat-treated alloy were measured using nanoindentation. Changes of nano-hardness and Young’s modulus of the A2 solid solution and D8<sub>m</sub> βNb<sub>5</sub>Si<sub>3</sub> per solute addition for this multiphase RCCA were discussed. The nano-hardness and Young’s modulus of the solid solution and the βNb<sub>5</sub>Si<sub>3</sub>, respectively, were 9.5 ± 0.2 GPa and 177.4 ± 5.5 GPa, and 17.55 ± 0.5 GPa and 250.27 ± 6.3 GPa after 200 h at 1500 °C. The aforementioned relationships and properties of the two phases demonstrated the importance of synergy and entanglement of solutes, parameters and phases in the microstructure and properties of the RCCA. Implications of synergy and entanglement for the design of metallic ultra-high temperature materials were emphasised.https://www.mdpi.com/2674-063X/3/1/5alloy designrefractory metal intermetallic compositesrefractory complex concentrated alloysrefractory high entropy alloysNb-silicide-based alloysbcc solid solution |
| spellingShingle | Nik Tankov Claire Utton Panos Tsakiropoulos On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated Alloy Alloys alloy design refractory metal intermetallic composites refractory complex concentrated alloys refractory high entropy alloys Nb-silicide-based alloys bcc solid solution |
| title | On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated Alloy |
| title_full | On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated Alloy |
| title_fullStr | On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated Alloy |
| title_full_unstemmed | On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated Alloy |
| title_short | On the Microstructure and Properties of Complex Concentrated bcc Solid Solution and Tetragonal D8<sub>m</sub> M<sub>5</sub>Si<sub>3</sub> Silicide Phases in a Refractory Complex Concentrated Alloy |
| title_sort | on the microstructure and properties of complex concentrated bcc solid solution and tetragonal d8 sub m sub m sub 5 sub si sub 3 sub silicide phases in a refractory complex concentrated alloy |
| topic | alloy design refractory metal intermetallic composites refractory complex concentrated alloys refractory high entropy alloys Nb-silicide-based alloys bcc solid solution |
| url | https://www.mdpi.com/2674-063X/3/1/5 |
| work_keys_str_mv | AT niktankov onthemicrostructureandpropertiesofcomplexconcentratedbccsolidsolutionandtetragonald8submsubmsub5subsisub3subsilicidephasesinarefractorycomplexconcentratedalloy AT claireutton onthemicrostructureandpropertiesofcomplexconcentratedbccsolidsolutionandtetragonald8submsubmsub5subsisub3subsilicidephasesinarefractorycomplexconcentratedalloy AT panostsakiropoulos onthemicrostructureandpropertiesofcomplexconcentratedbccsolidsolutionandtetragonald8submsubmsub5subsisub3subsilicidephasesinarefractorycomplexconcentratedalloy |