The relationship between pouring temperature and carburized microstructure of 1％Nb-added SCH13A heat-resistant cast steel manufactured by the self-hardening mold casting process at pouring temperatures of 1753 K, 1823 K and 1883 K was investigated. The creep properties of these materials subjected to repeated carburizing and quenching treatment were also examined. As a result, with increasing pouring temperature, the carburized depth decreases and the carbon concentration distribution in the carburized layer increases. A relative comparison of the creep properties revealed that the volume of primary carbides and the number of voids and micro-cracks in carbides generated due to repeated vacuum carburizing quenching treatment affected the creep rupture time. Creep rupture time of the carburized specimens was shorter than that of the as-cast specimens. Additionally, pouring at 1823 K exhibits the longest rupture time among the samples poured at three different temperatures.
{"title":"Changes in Carburized Microstructures and Creep Properties of Nb-Added SCH13A Heat-Resistant Cast Steel due to Different Pouring Temperatures","authors":"Tetsuya Okuyama, Ngo Huynh Kinh Luan, Masaki Kudo, Kuniaki Mizuno, Koreaki Koizumi","doi":"10.2320/jinstmet.j2023011","DOIUrl":"https://doi.org/10.2320/jinstmet.j2023011","url":null,"abstract":"The relationship between pouring temperature and carburized microstructure of 1％Nb-added SCH13A heat-resistant cast steel manufactured by the self-hardening mold casting process at pouring temperatures of 1753 K, 1823 K and 1883 K was investigated. The creep properties of these materials subjected to repeated carburizing and quenching treatment were also examined. As a result, with increasing pouring temperature, the carburized depth decreases and the carbon concentration distribution in the carburized layer increases. A relative comparison of the creep properties revealed that the volume of primary carbides and the number of voids and micro-cracks in carbides generated due to repeated vacuum carburizing quenching treatment affected the creep rupture time. Creep rupture time of the carburized specimens was shorter than that of the as-cast specimens. Additionally, pouring at 1823 K exhibits the longest rupture time among the samples poured at three different temperatures.","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135323393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper focuses on effect of rhodium addition on degradation behavior of Ir-10 mass％Rh alloy for a spark plug during oxidation at elevated temperatures. Oxidation tests were conducted at the temperature range from 1173 K to 1473 K in Ar-21％O2 gas mixture to clarify the effect of rhodium addition on degradation behavior of the alloy. As a result, there are three effects of rhodium addition to prevent the alloy from the degradation: (1) dissolution of rhodium into iridium oxide scale at below 1273 K, which decreases activity of iridium oxide in the oxide scale, (2) dissolution of rhodium into the alloy at above 1273 K, which decreases activity of iridium in the alloy and (3) formation of rhodium oxide, which decreases surface area of the alloy. All effects contribute to decrease vapor pressure of volatile iridium oxide, resulting in suppression of the degradation.
{"title":"The Effect of Rhodium Addition on Degradation Behavior of Ir-10 mass％Rh Alloy during Oxidation at Elevated Temperatures","authors":"Mitsutoshi Ueda, Kenta Terai, Shunsuke Yokota, Shunsuke Takeya, Hayato Yasuhara, Yosuke Imai","doi":"10.2320/jinstmet.j2023010","DOIUrl":"https://doi.org/10.2320/jinstmet.j2023010","url":null,"abstract":"This paper focuses on effect of rhodium addition on degradation behavior of Ir-10 mass％Rh alloy for a spark plug during oxidation at elevated temperatures. Oxidation tests were conducted at the temperature range from 1173 K to 1473 K in Ar-21％O2 gas mixture to clarify the effect of rhodium addition on degradation behavior of the alloy. As a result, there are three effects of rhodium addition to prevent the alloy from the degradation: (1) dissolution of rhodium into iridium oxide scale at below 1273 K, which decreases activity of iridium oxide in the oxide scale, (2) dissolution of rhodium into the alloy at above 1273 K, which decreases activity of iridium in the alloy and (3) formation of rhodium oxide, which decreases surface area of the alloy. All effects contribute to decrease vapor pressure of volatile iridium oxide, resulting in suppression of the degradation.","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135323367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.2320/jinstmet.j2023013
Kotaro Wada, Koichi Kitazono
Flame-retardant magnesium alloys prepared by adding calcium have been used as lightweight structural material. Thermomechanical treatments using hot rolling or hot extrusion are effective to improve the mechanical properties of flame-retardant magnesium alloys. This study focuses on the uniaxial hot pressing process for improving the mechanical properties of cast Mg-9Al-1Zn-2Ca alloy. The hot pressing tests were carried out with different temperatures up to 673 K and maximum compression strains of 65％. Microstructural characterization was carried out using a field-emission scanning electron microscope equipped with an electron back scattered diffraction system. 0.2％ proof stress, tensile strength and elongation to fracture were measured by a universal testing machine at room temperature. The Mg-9Al-1Zn-2Ca alloy showed the highest strength after the 65％ compression at 573 K, and the highest ductility after the 65％ compression at 673 K. The enhanced mechanical properties are attributed to grain refinement caused by dynamic recrystallization and reduced cavities due to the high compression strain.
加入钙制备的阻燃镁合金已被用作轻质结构材料。热轧或热挤压热处理是提高阻燃镁合金力学性能的有效方法。采用单轴热压工艺改善铸造Mg-9Al-1Zn-2Ca合金的力学性能。在不同温度下进行了热压试验，温度为673 K，最大压缩应变为65%。采用配备电子背散射衍射系统的场发射扫描电镜进行了微观结构表征。采用万能试验机在室温下测定0.2%的抗拉应力、抗拉强度和断裂伸长率。Mg-9Al-1Zn-2Ca合金在573 K 65%压缩后的强度最高，在673 K 65%压缩后的塑性最高。力学性能的提高是由于动态再结晶引起的晶粒细化和高压缩应变引起的空洞减少。
{"title":"高温プレスを利用した加工熱処理によるMg-9Al-1Zn-2Ca合金板の機械的特性向上","authors":"Kotaro Wada, Koichi Kitazono","doi":"10.2320/jinstmet.j2023013","DOIUrl":"https://doi.org/10.2320/jinstmet.j2023013","url":null,"abstract":"Flame-retardant magnesium alloys prepared by adding calcium have been used as lightweight structural material. Thermomechanical treatments using hot rolling or hot extrusion are effective to improve the mechanical properties of flame-retardant magnesium alloys. This study focuses on the uniaxial hot pressing process for improving the mechanical properties of cast Mg-9Al-1Zn-2Ca alloy. The hot pressing tests were carried out with different temperatures up to 673 K and maximum compression strains of 65％. Microstructural characterization was carried out using a field-emission scanning electron microscope equipped with an electron back scattered diffraction system. 0.2％ proof stress, tensile strength and elongation to fracture were measured by a universal testing machine at room temperature. The Mg-9Al-1Zn-2Ca alloy showed the highest strength after the 65％ compression at 573 K, and the highest ductility after the 65％ compression at 673 K. The enhanced mechanical properties are attributed to grain refinement caused by dynamic recrystallization and reduced cavities due to the high compression strain.","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135323648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To reduce the cost of solution heat treatment process Ni-base single crystal superalloy TMS-238 containing Re and Ru, quantitative analysis of dendrite-interdendrite segregation of alloying elements under various solution heat treatment conditions were conducted, and influence on high-temperature creep strength were investigated. In this study, we defined the solution rate Rsol (= (1 − Vf,e) × 100％, where Vf,e is volume fraction of eutectic γ′ that precipitates in the final solidification zone during casting) as a parameter to reveal the microstructure homogeneity. The Rsol values were 71％, 97％, 99％, 100％ for solutioning at 1250℃/20 h, 1320℃/5 h, 1320℃/20 h and 1335℃/20 h, respectively. Furthermore, it was confirmed that Re and W segregated in the dendrite core area and γ′ formers whereas Ta and Al segregated in the interdendrite. The magnitude of these segregations decreased as the solution temperature and time increased, and eventually the structure became almost homogeneous for solutioning at 1335℃ for 20 h. Additionally, creep test results indicate that Larson-Miller parameter (LMP) at 800℃-735 MPa, 900℃-392 MPa and 1000℃-245 MPa creep conditions show the same values for Rsol ≥ 97％. On the other hand, under 1100℃-137 MPa creep condition, LMP decreased as the Rsol decreased. A factor analysis of creep rupture properties suggested that the degradation of LMP under 1100℃-137 MPa was caused by the decrease of Re content and γ/γ′ lattice misfit in the interdendritic region.
{"title":"Ni基単結晶超合金TMS-238のデンドライト偏析とクリープ強度におよぼす溶体化熱処理の影響","authors":"Tadaharu Yokokawa, Toshio Osada, Chihiro Tabata, Takuma Kohata, Yuji Takata, Michinari Yuyama, Kyoko Kawagishi","doi":"10.2320/jinstmet.j2023004","DOIUrl":"https://doi.org/10.2320/jinstmet.j2023004","url":null,"abstract":"To reduce the cost of solution heat treatment process Ni-base single crystal superalloy TMS-238 containing Re and Ru, quantitative analysis of dendrite-interdendrite segregation of alloying elements under various solution heat treatment conditions were conducted, and influence on high-temperature creep strength were investigated. In this study, we defined the solution rate Rsol (= (1 − Vf,e) × 100％, where Vf,e is volume fraction of eutectic γ′ that precipitates in the final solidification zone during casting) as a parameter to reveal the microstructure homogeneity. The Rsol values were 71％, 97％, 99％, 100％ for solutioning at 1250℃/20 h, 1320℃/5 h, 1320℃/20 h and 1335℃/20 h, respectively. Furthermore, it was confirmed that Re and W segregated in the dendrite core area and γ′ formers whereas Ta and Al segregated in the interdendrite. The magnitude of these segregations decreased as the solution temperature and time increased, and eventually the structure became almost homogeneous for solutioning at 1335℃ for 20 h. Additionally, creep test results indicate that Larson-Miller parameter (LMP) at 800℃-735 MPa, 900℃-392 MPa and 1000℃-245 MPa creep conditions show the same values for Rsol ≥ 97％. On the other hand, under 1100℃-137 MPa creep condition, LMP decreased as the Rsol decreased. A factor analysis of creep rupture properties suggested that the degradation of LMP under 1100℃-137 MPa was caused by the decrease of Re content and γ/γ′ lattice misfit in the interdendritic region.","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136079920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hydrogen and Materials Characteristic in Solids V","authors":"Takayuki Ichikawa, Hiroki Miyaoka, Makoto Hino, Keitaro Horikawa, Teruto Kanadani","doi":"10.2320/jinstmet.jpr2023901","DOIUrl":"https://doi.org/10.2320/jinstmet.jpr2023901","url":null,"abstract":"","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135170500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, severe plastic deformation through high-pressure sliding (HPS) was applied for in situ high-energy X-ray diffraction analysis at SPring-8 in JASRI (Japan Synchrotron Radiation Research Institute). Allotropic transformation of pure Ti was examined in terms of temperatures, pressures and imposed strain using a miniaturized HPS facility. The true pressure applied on the sample was estimated from the peak shift. Peak broadening due to local variation of pressure was reduced using white X-ray. The phase transformation from α phase to ω phase occurred at a pressure of ∼4.5 GPa. Straining by the HPS processing was effective to promote the transformation to the ω phase and to maintain the ω phase even at ambient pressure. The reverse transformation from ω phase to α phase occurred at a temperature of ∼110℃ under ambient pressure, while under higher pressure as ∼4 GPa, the ω phase remained stable even at ∼170℃ covered in this study. It was suggested that the reverse transformation from the ω phase to the α phase is controlled by thermal energy.
{"title":"<i>In Situ</i> Synchrotron X-ray Analysis: Application of High-Pressure Sliding Process to Ti Allotropic Transformation","authors":"Zenji Horita, Daisuke Maruno, Yukimasa Ikeda, Takahiro Masuda, Yongpeng Tang, Makoto Arita, Yuji Higo, Yoshinori Tange, Yasuo Ohishi","doi":"10.2320/jinstmet.j2022040","DOIUrl":"https://doi.org/10.2320/jinstmet.j2022040","url":null,"abstract":"In this study, severe plastic deformation through high-pressure sliding (HPS) was applied for in situ high-energy X-ray diffraction analysis at SPring-8 in JASRI (Japan Synchrotron Radiation Research Institute). Allotropic transformation of pure Ti was examined in terms of temperatures, pressures and imposed strain using a miniaturized HPS facility. The true pressure applied on the sample was estimated from the peak shift. Peak broadening due to local variation of pressure was reduced using white X-ray. The phase transformation from α phase to ω phase occurred at a pressure of ∼4.5 GPa. Straining by the HPS processing was effective to promote the transformation to the ω phase and to maintain the ω phase even at ambient pressure. The reverse transformation from ω phase to α phase occurred at a temperature of ∼110℃ under ambient pressure, while under higher pressure as ∼4 GPa, the ω phase remained stable even at ∼170℃ covered in this study. It was suggested that the reverse transformation from the ω phase to the α phase is controlled by thermal energy.","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136153446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.2320/jinstmet.j2023031
You Yamashita, Yoshihiro Terada
The effect of Laves phases, C36–(Mg,Al)2Ca and C15–Al2Ca, on high-temperature creep strength was quantitatively investigated for the Mg–5.0Al–1.5Ca alloy produced by die-casting. The homogenization treatment at 750 K for 1 h was carried out to divorce the interconnected skeleton of C36 phase, and the aging treatment at 523 K for 1–1000 h was performed to precipitate the C15 phase within the α-Mg grains. The creep tests to evaluate the creep strength were conducted at 447 K and 70 MPa. When the C36 skeleton is divorced, the minimum creep rate dramatically increases by a factor of 330. The coarsening of the C15 phase within the α-Mg grains increases the creep rate by a factor of 2.6. It was identified that the creep strength of the Mg–5.0Al–1.5Ca alloy is predominantly ascribed to the interconnected skeleton of C36 phase rather than the precipitation strengthening of C15 phase.
{"title":"Mg–Al–Ca合金のクリープ強度に及ぼすラーベス相の影響","authors":"You Yamashita, Yoshihiro Terada","doi":"10.2320/jinstmet.j2023031","DOIUrl":"https://doi.org/10.2320/jinstmet.j2023031","url":null,"abstract":"The effect of Laves phases, C36–(Mg,Al)2Ca and C15–Al2Ca, on high-temperature creep strength was quantitatively investigated for the Mg–5.0Al–1.5Ca alloy produced by die-casting. The homogenization treatment at 750 K for 1 h was carried out to divorce the interconnected skeleton of C36 phase, and the aging treatment at 523 K for 1–1000 h was performed to precipitate the C15 phase within the α-Mg grains. The creep tests to evaluate the creep strength were conducted at 447 K and 70 MPa. When the C36 skeleton is divorced, the minimum creep rate dramatically increases by a factor of 330. The coarsening of the C15 phase within the α-Mg grains increases the creep rate by a factor of 2.6. It was identified that the creep strength of the Mg–5.0Al–1.5Ca alloy is predominantly ascribed to the interconnected skeleton of C36 phase rather than the precipitation strengthening of C15 phase.","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135562932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.2320/jinstmet.j2023012
Fumiya Wakamatsu, Hisao Kikugawa, Takashi Asaka
In this study, the oxidative degradation of gamma-irradiated ultra-high-molecular-weight polyethylene (UHMWPE) was evaluated. Tensile yield stress, Young's modulus, and Vickers hardness were measured to characterize oxidative deterioration. Furthermore, we evaluated the existence of residual radicals by the electron spin resonance (ESR) analysis, and discussed the relationship between ESR spectra change and mechanical property indexes. In the tensile test of small UHMWPE specimens, it is often difficult to measure the strain. Therefore, we tried to estimate the Young's modulus simply by using Hertz's theory of elastic contact, and confirmed its usefulness. It is possible to estimate the tensile Young's modulus from the indentation test in this experimental range. This method is applicable to evaluate the relationship between mechanical properties such as Young's modulus and ESR properties over a long term after irradiation.
{"title":"Evaluation of Oxidative Degradation of Ultra-High-Molecular-Weight Polyethylene Irradiated by Gamma-Ray","authors":"Fumiya Wakamatsu, Hisao Kikugawa, Takashi Asaka","doi":"10.2320/jinstmet.j2023012","DOIUrl":"https://doi.org/10.2320/jinstmet.j2023012","url":null,"abstract":"In this study, the oxidative degradation of gamma-irradiated ultra-high-molecular-weight polyethylene (UHMWPE) was evaluated. Tensile yield stress, Young's modulus, and Vickers hardness were measured to characterize oxidative deterioration. Furthermore, we evaluated the existence of residual radicals by the electron spin resonance (ESR) analysis, and discussed the relationship between ESR spectra change and mechanical property indexes. In the tensile test of small UHMWPE specimens, it is often difficult to measure the strain. Therefore, we tried to estimate the Young's modulus simply by using Hertz's theory of elastic contact, and confirmed its usefulness. It is possible to estimate the tensile Young's modulus from the indentation test in this experimental range. This method is applicable to evaluate the relationship between mechanical properties such as Young's modulus and ESR properties over a long term after irradiation.","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135562967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-03-01DOI: 10.2320/JINSTMET.J2017019
T. Tokunaga, Kazushi Sotomoto, M. Ohno, K. Matsuura
The poor corrosion resistance of Mg alloys, which is well known as one of the lightest structural metal materials, limits a wide use of these alloys. In order to dramatically increase not only the corrosion resistance but also the surface hardness of Mg alloys (AZ80), coating with A2024 Al alloy by hot extrusion has been attempted in this study. The coating was successfully realized by hot extrusion of a Mg alloy (AZ80) billet together with an Al alloy plate placed between the billet and the extrusion die. The A2024 Al alloy-coated Mg alloy exhibited an excellent corrosion resistance and no weight loss was observed after immersion in a 5 mass% HCl aqueous solution for 10 min while a weight loss of about 1500 g・m−2 was observed in case of AZ80 Mg alloy without coating under the same condition. The surface hardness of the coated alloy was increased to about 85 HV by aging for 144 h at room temperature after solution treatment for 3 h at 673 K. [doi:10.2320/matertrans.M2017317]
{"title":"Coating on Magnesium Alloy with Super Duralumin by Hot Extrusion and Evaluation of Its Surface Properties","authors":"T. Tokunaga, Kazushi Sotomoto, M. Ohno, K. Matsuura","doi":"10.2320/JINSTMET.J2017019","DOIUrl":"https://doi.org/10.2320/JINSTMET.J2017019","url":null,"abstract":"The poor corrosion resistance of Mg alloys, which is well known as one of the lightest structural metal materials, limits a wide use of these alloys. In order to dramatically increase not only the corrosion resistance but also the surface hardness of Mg alloys (AZ80), coating with A2024 Al alloy by hot extrusion has been attempted in this study. The coating was successfully realized by hot extrusion of a Mg alloy (AZ80) billet together with an Al alloy plate placed between the billet and the extrusion die. The A2024 Al alloy-coated Mg alloy exhibited an excellent corrosion resistance and no weight loss was observed after immersion in a 5 mass% HCl aqueous solution for 10 min while a weight loss of about 1500 g・m−2 was observed in case of AZ80 Mg alloy without coating under the same condition. The surface hardness of the coated alloy was increased to about 85 HV by aging for 144 h at room temperature after solution treatment for 3 h at 673 K. [doi:10.2320/matertrans.M2017317]","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"28 1","pages":"389-393"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79145963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-03-01DOI: 10.2320/JINSTMET.JA201601
Y. Gohda, Y. Tatetsu, S. Tsuneyuki
A fundamental understanding of microstructures is indispensable in improving neodymium-magnets performance at high temperatures. Thus, it is of signi cant importance to clarify atomic structures and local magnetic properties of interphase interfaces in microstructures, based on electron theory. We studied interfaces between the main phase of neodymium magnets, Nd2Fe14B, and a subphase NdOx using massively parallel rst-principles electronic-structure calculations with the K computer. As well as the known Cu-addition effect on wettability improvement in metallic Nd subphase, we recognized that some of the added Cu atoms at the (001) interface improve the local magnetic anisotropy of Nd at the interface. Furthermore, we found that the substitution of Fe in the (001)-surface of main-phase grains with Zn can also improve the stability of magnetic anisotropy. [doi:10.2320/matertrans.M2017258]
{"title":"Electron Theory on Grain-Boundary Structures and Local Magnetic Properties of Neodymium Magnets","authors":"Y. Gohda, Y. Tatetsu, S. Tsuneyuki","doi":"10.2320/JINSTMET.JA201601","DOIUrl":"https://doi.org/10.2320/JINSTMET.JA201601","url":null,"abstract":"A fundamental understanding of microstructures is indispensable in improving neodymium-magnets performance at high temperatures. Thus, it is of signi cant importance to clarify atomic structures and local magnetic properties of interphase interfaces in microstructures, based on electron theory. We studied interfaces between the main phase of neodymium magnets, Nd2Fe14B, and a subphase NdOx using massively parallel rst-principles electronic-structure calculations with the K computer. As well as the known Cu-addition effect on wettability improvement in metallic Nd subphase, we recognized that some of the added Cu atoms at the (001) interface improve the local magnetic anisotropy of Nd at the interface. Furthermore, we found that the substitution of Fe in the (001)-surface of main-phase grains with Zn can also improve the stability of magnetic anisotropy. [doi:10.2320/matertrans.M2017258]","PeriodicalId":17337,"journal":{"name":"Journal of The Japan Institute of Metals","volume":"462 1","pages":"26-31"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82980108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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