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On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys
The microstructures and hardness of the as cast and heat treated (1400 °C/100 h) alloys Nb-24Ti-18Si-5Ge-5Cr-5Al (ZF6) and Nb-24Ti-18Si-5Ge-5Cr-5Al-5Hf (ZF9) were studied. Both alloys were compared with refractory metal bcc solid solution + intermetallic High Entropy Alloys (HEAs). There was macrose...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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MDPI
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6747797/ https://www.ncbi.nlm.nih.gov/pubmed/31438493 http://dx.doi.org/10.3390/ma12172655 |
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author | Li, Zifu Tsakiropoulos, Panos |
author_facet | Li, Zifu Tsakiropoulos, Panos |
author_sort | Li, Zifu |
collection | PubMed |
description | The microstructures and hardness of the as cast and heat treated (1400 °C/100 h) alloys Nb-24Ti-18Si-5Ge-5Cr-5Al (ZF6) and Nb-24Ti-18Si-5Ge-5Cr-5Al-5Hf (ZF9) were studied. Both alloys were compared with refractory metal bcc solid solution + intermetallic High Entropy Alloys (HEAs). There was macrosegregation of Si, Ti, Cr and Al in both alloys. The roles of Ge and Hf on macrosegregation are discussed. In both alloys the primary phase was the βNb(5)Si(3). In the as cast alloy ZF6 the Nb(ss), βNb(5)Si(3) and C14-NbCr(2) Laves phase and Nb(ss) + βNb(5)Si(3) eutectic were formed. The microstructure of the as cast alloy ZF9 consisted of Nb(ss), βNb(5)Si(3), γNb(5)Si(3) and C14-NbCr(2) Laves phase. The heat-treated microstructures of the alloys ZF6 and ZF9 consisted of Nb(ss), βNb(5)Si(3) and αNb(5)Si(3) and Nb(ss), βNb(5)Si(3,) αNb(5)Si(3) and γNb(5)Si(3), respectively. The surfaces of both alloys were contaminated by oxygen where TiO(2) and HfO(2) formed respectively in the alloys ZF6 and ZF9. Alloying with Hf increased the lattice parameter of Nb(ss) and decreased the hardness of ZF9 and Nb(5)Si(3). The roles of alloying additions on the hardness of the Nb(ss) and Nb(5)Si(3) and relationships between alloy hardness and alloy parameters VEC (valence electron concentration), δ (related to atomic size) and Δχ (related to electronegativity) were discussed. |
format | Online Article Text |
id | pubmed-6747797 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-67477972019-09-27 On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys Li, Zifu Tsakiropoulos, Panos Materials (Basel) Article The microstructures and hardness of the as cast and heat treated (1400 °C/100 h) alloys Nb-24Ti-18Si-5Ge-5Cr-5Al (ZF6) and Nb-24Ti-18Si-5Ge-5Cr-5Al-5Hf (ZF9) were studied. Both alloys were compared with refractory metal bcc solid solution + intermetallic High Entropy Alloys (HEAs). There was macrosegregation of Si, Ti, Cr and Al in both alloys. The roles of Ge and Hf on macrosegregation are discussed. In both alloys the primary phase was the βNb(5)Si(3). In the as cast alloy ZF6 the Nb(ss), βNb(5)Si(3) and C14-NbCr(2) Laves phase and Nb(ss) + βNb(5)Si(3) eutectic were formed. The microstructure of the as cast alloy ZF9 consisted of Nb(ss), βNb(5)Si(3), γNb(5)Si(3) and C14-NbCr(2) Laves phase. The heat-treated microstructures of the alloys ZF6 and ZF9 consisted of Nb(ss), βNb(5)Si(3) and αNb(5)Si(3) and Nb(ss), βNb(5)Si(3,) αNb(5)Si(3) and γNb(5)Si(3), respectively. The surfaces of both alloys were contaminated by oxygen where TiO(2) and HfO(2) formed respectively in the alloys ZF6 and ZF9. Alloying with Hf increased the lattice parameter of Nb(ss) and decreased the hardness of ZF9 and Nb(5)Si(3). The roles of alloying additions on the hardness of the Nb(ss) and Nb(5)Si(3) and relationships between alloy hardness and alloy parameters VEC (valence electron concentration), δ (related to atomic size) and Δχ (related to electronegativity) were discussed. MDPI 2019-08-21 /pmc/articles/PMC6747797/ /pubmed/31438493 http://dx.doi.org/10.3390/ma12172655 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Li, Zifu Tsakiropoulos, Panos On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys |
title | On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys |
title_full | On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys |
title_fullStr | On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys |
title_full_unstemmed | On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys |
title_short | On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys |
title_sort | on the microstructures and hardness of the nb-24ti-18si-5al-5cr-5ge and nb-24ti-18si-5al-5cr-5ge-5hf (at.%) silicide based alloys |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6747797/ https://www.ncbi.nlm.nih.gov/pubmed/31438493 http://dx.doi.org/10.3390/ma12172655 |
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