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Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior

An HfC-doped molybdenum (Mo-Hf-C; MHC) alloy was prepared via a powder metallurgy process, including dry direct doping followed by ball-milling, cold-isotactic-pressing, and vacuum sintering. An oxidation comparison experiment was conducted, and the oxidation and volatilization behaviors were analyz...

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Autores principales: Wang, Miao, Yang, Shuangping, Dong, Jie, Sun, Haixing, Liu, Shouman
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8911783/
https://www.ncbi.nlm.nih.gov/pubmed/35269189
http://dx.doi.org/10.3390/ma15051958
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author Wang, Miao
Yang, Shuangping
Dong, Jie
Sun, Haixing
Liu, Shouman
author_facet Wang, Miao
Yang, Shuangping
Dong, Jie
Sun, Haixing
Liu, Shouman
author_sort Wang, Miao
collection PubMed
description An HfC-doped molybdenum (Mo-Hf-C; MHC) alloy was prepared via a powder metallurgy process, including dry direct doping followed by ball-milling, cold-isotactic-pressing, and vacuum sintering. An oxidation comparison experiment was conducted, and the oxidation and volatilization behaviors were analyzed using the mass change, volatile generation rate, and morphology transformation. The results show that relatively uniform powder morphology can be obtained by the direct doping of carbide and high-energy ball milling. The oxidation of the MHC alloy at a lower temperature was characterized by the oxygen-absorption and a slight weight gain, while at a higher temperature and longer holding time, it was characterized by the mass volatile weight loss. A significant weight change appeared at 800 °C for 30 min with a weight loss rate of 4.8%. Surface oxidation products developed horizontally from ridged oxides at lower temperature stages to a flaky oxide layer at higher temperatures. The peeling of the oxide layer was the result of interfacial pore development, which led to exposure of the alloy matrix and further oxidation. Based on the oxidation and volatilization characteristics of HfC-doped MHC alloys, we conclude that the oxidation and volatilization of the MHC alloy conformed to the general law; however, the significant weight loss temperature, weight loss rate, volatilization temperature, and volatilization rate were improved compared with pure molybdenum and traditional molybdenum alloys, thus, indicating that the precipitation of the second phase HfC particles at the grain boundaries and within the grains can inhibit the oxidation and volatilization of matrix elements to a certain extent.
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spelling pubmed-89117832022-03-11 Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior Wang, Miao Yang, Shuangping Dong, Jie Sun, Haixing Liu, Shouman Materials (Basel) Article An HfC-doped molybdenum (Mo-Hf-C; MHC) alloy was prepared via a powder metallurgy process, including dry direct doping followed by ball-milling, cold-isotactic-pressing, and vacuum sintering. An oxidation comparison experiment was conducted, and the oxidation and volatilization behaviors were analyzed using the mass change, volatile generation rate, and morphology transformation. The results show that relatively uniform powder morphology can be obtained by the direct doping of carbide and high-energy ball milling. The oxidation of the MHC alloy at a lower temperature was characterized by the oxygen-absorption and a slight weight gain, while at a higher temperature and longer holding time, it was characterized by the mass volatile weight loss. A significant weight change appeared at 800 °C for 30 min with a weight loss rate of 4.8%. Surface oxidation products developed horizontally from ridged oxides at lower temperature stages to a flaky oxide layer at higher temperatures. The peeling of the oxide layer was the result of interfacial pore development, which led to exposure of the alloy matrix and further oxidation. Based on the oxidation and volatilization characteristics of HfC-doped MHC alloys, we conclude that the oxidation and volatilization of the MHC alloy conformed to the general law; however, the significant weight loss temperature, weight loss rate, volatilization temperature, and volatilization rate were improved compared with pure molybdenum and traditional molybdenum alloys, thus, indicating that the precipitation of the second phase HfC particles at the grain boundaries and within the grains can inhibit the oxidation and volatilization of matrix elements to a certain extent. MDPI 2022-03-07 /pmc/articles/PMC8911783/ /pubmed/35269189 http://dx.doi.org/10.3390/ma15051958 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/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 (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Wang, Miao
Yang, Shuangping
Dong, Jie
Sun, Haixing
Liu, Shouman
Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior
title Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior
title_full Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior
title_fullStr Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior
title_full_unstemmed Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior
title_short Preparation of an MHC Alloy by Direct Doping of HfC and Its High Temperature Oxidation and Volatilization Behavior
title_sort preparation of an mhc alloy by direct doping of hfc and its high temperature oxidation and volatilization behavior
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8911783/
https://www.ncbi.nlm.nih.gov/pubmed/35269189
http://dx.doi.org/10.3390/ma15051958
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