Pub Date : 2000-12-01DOI: 10.2320/MATERTRANS1989.41.1646
T. Akashi, Toshihiko Inoue, T. Maruyama
Electrical conductivity measurements are used here to estimate the Gibbs energy change for formation of ternary oxide from binary oxides. The theoretical background and the advantages of the present method are discussed. As a demonstration, the standard Gibbs energy change of the reaction, Sr 3 Cr 2 O 8 + 1/2Cr 2 O 3 + 5/4O 2 → 3SrCrO 4 was estimated by electrical conductivity measurements of two kinds of Sr 3 Cr 2 O 8 oxides, one equilibrated with Sr 3 Cr 2 O 8 and the other with Cr 2 O 3 . The standard Gibbs energy change of the reaction is obtained as ΔG°/kJ mol -1 = -409 + 0.252T (±10), 1323 ∼ 1373 K. The resulting value is in good agreement with that obtained by measurement of the equilibrium oxygen pressure using a solid oxygen concentration cell.
{"title":"Electrical Conductivity Measurement for Estimation of Standard Gibbs Energy Change of Ternary Oxide Formation","authors":"T. Akashi, Toshihiko Inoue, T. Maruyama","doi":"10.2320/MATERTRANS1989.41.1646","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1646","url":null,"abstract":"Electrical conductivity measurements are used here to estimate the Gibbs energy change for formation of ternary oxide from binary oxides. The theoretical background and the advantages of the present method are discussed. As a demonstration, the standard Gibbs energy change of the reaction, Sr 3 Cr 2 O 8 + 1/2Cr 2 O 3 + 5/4O 2 → 3SrCrO 4 was estimated by electrical conductivity measurements of two kinds of Sr 3 Cr 2 O 8 oxides, one equilibrated with Sr 3 Cr 2 O 8 and the other with Cr 2 O 3 . The standard Gibbs energy change of the reaction is obtained as ΔG°/kJ mol -1 = -409 + 0.252T (±10), 1323 ∼ 1373 K. The resulting value is in good agreement with that obtained by measurement of the equilibrium oxygen pressure using a solid oxygen concentration cell.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"58 1","pages":"1646-1650"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73661937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2320/MATERTRANS1989.41.1636
A. Nishimoto, M. Ando, M. Takahashi, M. Aritoshi, K. Ikeuchi
Intermediate layers of various metals ranging from reactive metals to noble metals have been applied to friction bonding of SiC (pressureless-sintered silicon carbide) to Cu (oxygen-free copper), and their influences on the bond strength and microstructures of the joint have been systematically investigated by means of TEM observations. When a thin foil of reactive metal, Al, Ti, Zr, or Nb, was applied as the intermediate layer, the bond strength of SiC to Cu was improved considerably. In contrast, when an intermediate layer of Fe, Ni, or Ag was applied, the SiC specimen separated from the Cu specimen immediately after the bonding operation without the application of external load, similar to the case of bonding without an intermediate layer. During friction bonding with an intermediate layer of reactive metal, the intermediate layer was mechanically mixed with Cu lo form a very complicated microstructure extending over a region as wide as a few 100 μm TEM observations have revealed that very thin reaction layers between the SiC and reactive metals were formed. When the Ti intermediate layer was applied, a TiC layer 10-30 nm thick was formed over almost the entire area along the interface, and between this layer and the SiC matrix a very thin layer of a Cu solid solution was detected. On the other side of the TiC layer, a Ti 5 Si 3 layer ∼100 nm thick was partially observed. When the Nb or Zr intermediate layer was applied, a very thin interfacial layer, in which Nb or Zr was significantly concentrated, was observed in addition to the reaction layers of Nb 5 Si 3 , NbC, and ZrC. These interfacial layers can he characterized by their much smaller thickness and finer grain size than those observed in diffusion-bonded and brazed joints. Apart from the layers mentioned above, amorphous silicon oxide layers were occasionally observed, suggesting that the reactive metal enhanced the removal of the oxide film on the SiC surface.
在无压烧结碳化硅(SiC)与无氧铜(Cu)的摩擦结合中，应用了从活性金属到贵金属的各种金属中间层，并通过TEM观察系统地研究了它们对结合强度和接头显微组织的影响。采用活性金属(Al、Ti、Zr或Nb)薄膜作为中间层，SiC与Cu的结合强度显著提高。相反，当施加Fe、Ni或Ag中间层时，在不施加外载荷的情况下，SiC试样在键合操作后立即从Cu试样中分离出来，类似于没有中间层的键合情况。在与活性金属中间层的摩擦键合过程中，中间层与Cu - lo机械混合形成一个非常复杂的微观结构，延伸到几个100 μm的区域，TEM观察显示，在SiC和活性金属之间形成了非常薄的反应层。当Ti中间层加入后，沿界面几乎整个区域形成了一层10 ~ 30nm厚的TiC层，并且在该层与SiC基体之间形成了一层极薄的Cu固溶体。在TiC层的另一侧，部分观察到厚度约100 nm的Ti 5 Si 3层。当施加Nb或Zr中间层时，除了Nb 5 Si 3、NbC和ZrC的反应层外，还观察到Nb或Zr显著富集的极薄界面层。这些界面层具有比扩散焊和钎焊界面层更小的厚度和更细的晶粒尺寸。除了上述层外，偶尔还观察到非晶氧化硅层，这表明活性金属增强了SiC表面氧化膜的去除。
{"title":"Friction Bonding of Silicon Carbide to Oxygen-Free Copper with an Intermediate Layer of Reactive Metal","authors":"A. Nishimoto, M. Ando, M. Takahashi, M. Aritoshi, K. Ikeuchi","doi":"10.2320/MATERTRANS1989.41.1636","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1636","url":null,"abstract":"Intermediate layers of various metals ranging from reactive metals to noble metals have been applied to friction bonding of SiC (pressureless-sintered silicon carbide) to Cu (oxygen-free copper), and their influences on the bond strength and microstructures of the joint have been systematically investigated by means of TEM observations. When a thin foil of reactive metal, Al, Ti, Zr, or Nb, was applied as the intermediate layer, the bond strength of SiC to Cu was improved considerably. In contrast, when an intermediate layer of Fe, Ni, or Ag was applied, the SiC specimen separated from the Cu specimen immediately after the bonding operation without the application of external load, similar to the case of bonding without an intermediate layer. During friction bonding with an intermediate layer of reactive metal, the intermediate layer was mechanically mixed with Cu lo form a very complicated microstructure extending over a region as wide as a few 100 μm TEM observations have revealed that very thin reaction layers between the SiC and reactive metals were formed. When the Ti intermediate layer was applied, a TiC layer 10-30 nm thick was formed over almost the entire area along the interface, and between this layer and the SiC matrix a very thin layer of a Cu solid solution was detected. On the other side of the TiC layer, a Ti 5 Si 3 layer ∼100 nm thick was partially observed. When the Nb or Zr intermediate layer was applied, a very thin interfacial layer, in which Nb or Zr was significantly concentrated, was observed in addition to the reaction layers of Nb 5 Si 3 , NbC, and ZrC. These interfacial layers can he characterized by their much smaller thickness and finer grain size than those observed in diffusion-bonded and brazed joints. Apart from the layers mentioned above, amorphous silicon oxide layers were occasionally observed, suggesting that the reactive metal enhanced the removal of the oxide film on the SiC surface.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"41 1","pages":"1636-1645"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78101243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2320/MATERTRANS1989.41.1589
Jifan Hu, H. Qin, Shao-xiong Zhou, Yi-zhong Wang, Zhenxi Wang
In the present paper, the dc longitudinal field and ac frequency dependence of the magnetoimpedance, magnetoresistance, magnetoreactance and magnetoimpedance-phase of NiFeMo permalloy ribbon are investigated. The value of the magnetoimpedance ratio (Z(0) - Z(5172A.m -1 ))/Z(0) of NiFeMo permalloy ribbon can reach 39.54% at 0.3MHz. We also found that the change ratios of the magnetoimpedance (Z(0) - Z(5172A.m -1 ))/Z(0), the magnetoresistance ratio (R(0) - R(5172 A.m -1 )))/R(0) and the magnetoreactance ratio (X(0) - X(5172A.m -1 ))/X(0) intersect at 0.27 MHz where the change ratio of the magnetoimpedance phase (θ(0)-θ(5172A.m -1 ))/θ(0) is zero.
{"title":"Giant Magnetoimpedance Effect in NiFeMo Permalloy Ribbon","authors":"Jifan Hu, H. Qin, Shao-xiong Zhou, Yi-zhong Wang, Zhenxi Wang","doi":"10.2320/MATERTRANS1989.41.1589","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1589","url":null,"abstract":"In the present paper, the dc longitudinal field and ac frequency dependence of the magnetoimpedance, magnetoresistance, magnetoreactance and magnetoimpedance-phase of NiFeMo permalloy ribbon are investigated. The value of the magnetoimpedance ratio (Z(0) - Z(5172A.m -1 ))/Z(0) of NiFeMo permalloy ribbon can reach 39.54% at 0.3MHz. We also found that the change ratios of the magnetoimpedance (Z(0) - Z(5172A.m -1 ))/Z(0), the magnetoresistance ratio (R(0) - R(5172 A.m -1 )))/R(0) and the magnetoreactance ratio (X(0) - X(5172A.m -1 ))/X(0) intersect at 0.27 MHz where the change ratio of the magnetoimpedance phase (θ(0)-θ(5172A.m -1 ))/θ(0) is zero.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"65 1","pages":"1589-1592"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83741365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2320/MATERTRANS1989.41.1679
Wei Zhang, A. Inoue
New Fe-based glassy alloys in Fe-Co-Nd-Dy-B system with high boron concentrations were found to exhibit a wide supercooled liquid region exceeding 50 K. The high stability of the supercooled liquid enabled us to produce cylindrical bulk glassy alloys with diameters up to 0.75 mm by copper mold casting. The glass transition temperature (T g ), crystallization temperature (T x ), supercooled liquid region ΔT x (=T x - T g ) and heat of crystallization of the Φ0.75 mm rod of glassy Fe 62 Co 9.5 Nd 3 Dy 0.5 B 25 alloy are 844 K, 899 K, 55 K and 4.46 kJ/mol, respectively. No appreciable difference in the thermal stability is seen between the bulk rods and melt-spun ribbon. The saturation magnetization (I s ), coercive force (H c ), saturated magnetostriction (λ s ) and Curie temperature (T c ) of the melt-spun Fe 62 Co 9,5 Nd 3 Dy 0.5 B 25 ribbon are 1.37T, T, 4.58 A/m, 17.9 × 10 -6 and 663 K, respectively, and I s and T c are nearly the same as those for the bulk glass rods with diameters of 0.5 and 0.75 mm. The success of forming the Fe-based bulk glassy alloys exhibiting good soft magnetic properties is promising for future development as a new type of soft magnetic material.
在Fe-Co-Nd-Dy-B体系中发现了高硼浓度的新型铁基非晶合金，其过冷区超过50 K。过冷液体的高稳定性使我们能够通过铜模铸造生产直径高达0.75毫米的圆柱形大块玻璃合金。Fe 62 Co 9.5 Nd 3 Dy 0.5 b25合金的玻璃化转变温度(T g)、结晶温度(T x)、过冷液区ΔT x (=T x - T g)和Φ0.75 mm棒的结晶热分别为844 K、899 K、55 K和4.46 kJ/mol。块状棒和熔纺带在热稳定性方面没有明显的差别。熔融纺丝fe62co9,5nd3dy0.5 b25带的饱和磁化强度(I s)、矫顽力(H c)、饱和磁致伸缩(λ s)和居里温度(T c)分别为1.37T、4.58 A/m、17.9 × 10 -6和663 K，与直径为0.5和0.75 mm的大块玻璃棒的I s和T c基本相同。成功制备出具有良好软磁性能的铁基块状玻璃合金，是一种新型软磁材料，具有广阔的发展前景。
{"title":"Formation and magnetic properties of bulk glassy Fe-Co-Nd-Dy-B alloys with high boron concentrations","authors":"Wei Zhang, A. Inoue","doi":"10.2320/MATERTRANS1989.41.1679","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1679","url":null,"abstract":"New Fe-based glassy alloys in Fe-Co-Nd-Dy-B system with high boron concentrations were found to exhibit a wide supercooled liquid region exceeding 50 K. The high stability of the supercooled liquid enabled us to produce cylindrical bulk glassy alloys with diameters up to 0.75 mm by copper mold casting. The glass transition temperature (T g ), crystallization temperature (T x ), supercooled liquid region ΔT x (=T x - T g ) and heat of crystallization of the Φ0.75 mm rod of glassy Fe 62 Co 9.5 Nd 3 Dy 0.5 B 25 alloy are 844 K, 899 K, 55 K and 4.46 kJ/mol, respectively. No appreciable difference in the thermal stability is seen between the bulk rods and melt-spun ribbon. The saturation magnetization (I s ), coercive force (H c ), saturated magnetostriction (λ s ) and Curie temperature (T c ) of the melt-spun Fe 62 Co 9,5 Nd 3 Dy 0.5 B 25 ribbon are 1.37T, T, 4.58 A/m, 17.9 × 10 -6 and 663 K, respectively, and I s and T c are nearly the same as those for the bulk glass rods with diameters of 0.5 and 0.75 mm. The success of forming the Fe-based bulk glassy alloys exhibiting good soft magnetic properties is promising for future development as a new type of soft magnetic material.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"10 1","pages":"1679-1682"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78577363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2320/MATERTRANS1989.41.1621
Kazunori Sato, K. Sakamaki, Y. Inoue
A new electrocatalyst which enables direct methane use in solid oxide fuel cells (SOFCs) was examined. The dispersion of Co 0.5 Ni 0.5 O particles into a porous-platinum-based anode increased the cell performance in an SOFC using a stabilized-zirconia electrolyte. Among the catalysts studied, Co 0.5 Ni 0.5 O, CoO, and NiO, the increase was the most prominent for Co 0.5 Ni 0.5 O. The anodic polarization resistance and the production rates of CO, CO 2 , and H 2 in the outlet gas showed a high Co 0.5 Ni 0.5 O catalytic activity for the electrochemical oxidation of methane, indicating the activation of the steam-reforming reaction caused by the formation of surface active sites in relation to the cation vacancy in the CoO-NiO solid solution.
研究了一种能直接在固体氧化物燃料电池(SOFCs)中使用甲烷的新型电催化剂。Co 0.5 Ni 0.5 O颗粒分散到多孔铂基阳极中，使用稳定的氧化锆电解质提高了SOFC电池的性能。催化剂研究中,公司0.5镍0.5 O,首席运营官,NiO,最突出的为公司增加0.5镍0.5 O .阳极极化电阻率和生产有限公司有限公司2和H 2出口气体显示高有限公司0.5镍0.5 O电化学氧化甲烷的催化活性,表明激活引起的蒸汽重整反应的形成与阳离子表面活性网站CoO-NiO固溶体的空缺。
{"title":"Electrocatalytic Activity of Co0.5Ni0.5O Particles for the Anodic Oxidation of Methane","authors":"Kazunori Sato, K. Sakamaki, Y. Inoue","doi":"10.2320/MATERTRANS1989.41.1621","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1621","url":null,"abstract":"A new electrocatalyst which enables direct methane use in solid oxide fuel cells (SOFCs) was examined. The dispersion of Co 0.5 Ni 0.5 O particles into a porous-platinum-based anode increased the cell performance in an SOFC using a stabilized-zirconia electrolyte. Among the catalysts studied, Co 0.5 Ni 0.5 O, CoO, and NiO, the increase was the most prominent for Co 0.5 Ni 0.5 O. The anodic polarization resistance and the production rates of CO, CO 2 , and H 2 in the outlet gas showed a high Co 0.5 Ni 0.5 O catalytic activity for the electrochemical oxidation of methane, indicating the activation of the steam-reforming reaction caused by the formation of surface active sites in relation to the cation vacancy in the CoO-NiO solid solution.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"48 1","pages":"1621-1625"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78252163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2320/MATERTRANS1989.41.1612
O. Uemura, Keigo Abe, Ryoki Uejyoh, T. Usuki, Y. Kameda
The short-range atomic order in amorphous and liquid ZnSnAs 2 has been studied with electron diffraction and neutron diffraction. It has been shown that the local structure in amorphous ZnSnAs 2 maintains the crystalline chalcopyrite structure, in which a central As atom is tetrahedrally surrounded by two Zn and two Sn atoms, while, its crystalline atomic order is markedly broken in the liquid phase, accompanying a change of the bonding nature. The structure in the liquid phase is considered to be similar to that in liquid metals. The structural and bonding differences in solid and liquid phases correspond reasonably to a rapid increase of the electrical conductivity and paramagnetic susceptibility on melting. The short-range structure in amorphous and liquid ZnSnAs 2 has been discussed referring to the related crystalline lattices.
{"title":"The Short-Range Atomic Order in Amorphous and Liquid ZnSnAs2","authors":"O. Uemura, Keigo Abe, Ryoki Uejyoh, T. Usuki, Y. Kameda","doi":"10.2320/MATERTRANS1989.41.1612","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1612","url":null,"abstract":"The short-range atomic order in amorphous and liquid ZnSnAs 2 has been studied with electron diffraction and neutron diffraction. It has been shown that the local structure in amorphous ZnSnAs 2 maintains the crystalline chalcopyrite structure, in which a central As atom is tetrahedrally surrounded by two Zn and two Sn atoms, while, its crystalline atomic order is markedly broken in the liquid phase, accompanying a change of the bonding nature. The structure in the liquid phase is considered to be similar to that in liquid metals. The structural and bonding differences in solid and liquid phases correspond reasonably to a rapid increase of the electrical conductivity and paramagnetic susceptibility on melting. The short-range structure in amorphous and liquid ZnSnAs 2 has been discussed referring to the related crystalline lattices.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"2 1","pages":"1612-1615"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85329848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-11-20DOI: 10.2320/MATERTRANS1989.41.1435
N. Pryds, M. Eldrup, M. Ohnuma, A. Pedersen, J. Hattel, S. Linderoth
Bulk amorphous (Mg 1-y Al y ) 60 Cu 30 Y 10 alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs. time was recorded during the cooling and solidilication process of the melt and compared with a spacial and temporal numerical simulation of that process. It is concluded that good thermal contact is maintained between the amorphous part of the solidified sample and the mould, while a rather poor contact develops between the crystalline part of the sample and the mould, probably due to the appearance of a narrow gap at the crystal-mould interface during crystallisation. The maximum amorphous layer thickness decreases from ∼3 mm to zero when the Al content increases in the range from 0 to about y = 10%. The evolution of the microstructure of the initially amorphous phase was examined by x-ray diffraction (XRD) and differential scanning calorimetry (DSC) for different alloy compositions and annealing temperatures. On annealing into the supercooled liquid state (441 K), specimens with no Al content remain basically amorphous while nanoparticles are formed and remain stable also at higher temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg 60 Cu 30 Y 10 specimen was determined experimentally by a combination of DSC data and temperature vs. time measurements to be 60-150 K/s, in agreement with estimates from the literature. The Vickers hardness (H V ) of the amorphous material for y = 2% is higher (∼360 kg/mm 2 ) than for y = 0 (∼290 kg/mm 2 ). On crystallisation the hardness of the latter material increases to the 400 kg/mm 2 level while the hardness of the former does not change.
{"title":"Preparation and Properties of Mg–Cu–Y–Al Bulk Amorphous Alloys","authors":"N. Pryds, M. Eldrup, M. Ohnuma, A. Pedersen, J. Hattel, S. Linderoth","doi":"10.2320/MATERTRANS1989.41.1435","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1435","url":null,"abstract":"Bulk amorphous (Mg 1-y Al y ) 60 Cu 30 Y 10 alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs. time was recorded during the cooling and solidilication process of the melt and compared with a spacial and temporal numerical simulation of that process. It is concluded that good thermal contact is maintained between the amorphous part of the solidified sample and the mould, while a rather poor contact develops between the crystalline part of the sample and the mould, probably due to the appearance of a narrow gap at the crystal-mould interface during crystallisation. The maximum amorphous layer thickness decreases from ∼3 mm to zero when the Al content increases in the range from 0 to about y = 10%. The evolution of the microstructure of the initially amorphous phase was examined by x-ray diffraction (XRD) and differential scanning calorimetry (DSC) for different alloy compositions and annealing temperatures. On annealing into the supercooled liquid state (441 K), specimens with no Al content remain basically amorphous while nanoparticles are formed and remain stable also at higher temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg 60 Cu 30 Y 10 specimen was determined experimentally by a combination of DSC data and temperature vs. time measurements to be 60-150 K/s, in agreement with estimates from the literature. The Vickers hardness (H V ) of the amorphous material for y = 2% is higher (∼360 kg/mm 2 ) than for y = 0 (∼290 kg/mm 2 ). On crystallisation the hardness of the latter material increases to the 400 kg/mm 2 level while the hardness of the former does not change.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"16 1","pages":"1435-1442"},"PeriodicalIF":0.0,"publicationDate":"2000-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79361296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-11-20DOI: 10.2320/MATERTRANS1989.41.1562
M. Pérez-Prado, M. Cristina, O. Ruano, G. González-Doncel
The texture evolution of the Al-Li alloy 8090 has been investigated in order to analyze the microscopic mechanisms operative during deformation under different conditions of temperature and strain rate. A through-thickness texture gradient is present in the as-received material. As will be seen, the predominant deformation mechanisms are different in the mid layer and in the outer regions of the 8090 sheet alloy. In the outer regions, the texture intensity decreases with deformation and no significant changes in the main components were observed, indicating the predominance of grain boundary sliding (GBS). In the mid-layer, however, texture sharpens with straining and major changes in the main texture components were detected, revealing that crystallographic slip (CS) plays an important role in the deformation of this zone. CS takes place mainly in two slip systems and causes the orientations to move along the β-fiber in Euler space, towards the Copper component in longitudinal tests and towards the Brass component in transverse tests. The comparably small ductility of the 8090 alloy, with respect to other similar superplastic aluminum alloys, may be due to the operation of CS in the mid-layer.
{"title":"Deformation Mechanisms of Superplastic Al–Li 8090 Alloy Examined by X-Ray Texture Measurements","authors":"M. Pérez-Prado, M. Cristina, O. Ruano, G. González-Doncel","doi":"10.2320/MATERTRANS1989.41.1562","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1562","url":null,"abstract":"The texture evolution of the Al-Li alloy 8090 has been investigated in order to analyze the microscopic mechanisms operative during deformation under different conditions of temperature and strain rate. A through-thickness texture gradient is present in the as-received material. As will be seen, the predominant deformation mechanisms are different in the mid layer and in the outer regions of the 8090 sheet alloy. In the outer regions, the texture intensity decreases with deformation and no significant changes in the main components were observed, indicating the predominance of grain boundary sliding (GBS). In the mid-layer, however, texture sharpens with straining and major changes in the main texture components were detected, revealing that crystallographic slip (CS) plays an important role in the deformation of this zone. CS takes place mainly in two slip systems and causes the orientations to move along the β-fiber in Euler space, towards the Copper component in longitudinal tests and towards the Brass component in transverse tests. The comparably small ductility of the 8090 alloy, with respect to other similar superplastic aluminum alloys, may be due to the operation of CS in the mid-layer.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"2 1","pages":"1562-1568"},"PeriodicalIF":0.0,"publicationDate":"2000-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78369531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-11-20DOI: 10.2320/MATERTRANS1989.41.1555
W. Lu, Di Zhang, Xiaonong Zhang, R. Wu, T. Sakata, H. Mori
TiB and TiC reinforced titanium matrix composites have been produced by non-consumable arc-melting technology utilizing the self-propagation high-temperature synthesis reactions between titanium and B 4 C, graphite. X-ray diffraction (XRD) was used to identify the phases in the composites. Microstructures of composites have been observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HREM). The results show that there are three phases in the composite: TiB, TiC and titanium matrix alloy, Reinforcements are distributed uniformly in the matrix. TiB grows in short-fiber shape and TiC grows in dendritic, equiaxed shapes. The interfaces between reinforcements and titanium matrix alloy are very clean. There is no any interfacial reaction. There are high-density dislocations around TiC particle. Mechanical properties have been improved due to the incorporation of reinforcements. The addition of aluminum not only strengthens the titanium matrix alloy by solid solution strengthening, but also improves the mechanical properties of composites by refining the reinforcements and matrix alloy.
{"title":"Microstructure and Compressive Properties of In Situ Synthesized (TiB + TiC)/Ti Composites","authors":"W. Lu, Di Zhang, Xiaonong Zhang, R. Wu, T. Sakata, H. Mori","doi":"10.2320/MATERTRANS1989.41.1555","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1555","url":null,"abstract":"TiB and TiC reinforced titanium matrix composites have been produced by non-consumable arc-melting technology utilizing the self-propagation high-temperature synthesis reactions between titanium and B 4 C, graphite. X-ray diffraction (XRD) was used to identify the phases in the composites. Microstructures of composites have been observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HREM). The results show that there are three phases in the composite: TiB, TiC and titanium matrix alloy, Reinforcements are distributed uniformly in the matrix. TiB grows in short-fiber shape and TiC grows in dendritic, equiaxed shapes. The interfaces between reinforcements and titanium matrix alloy are very clean. There is no any interfacial reaction. There are high-density dislocations around TiC particle. Mechanical properties have been improved due to the incorporation of reinforcements. The addition of aluminum not only strengthens the titanium matrix alloy by solid solution strengthening, but also improves the mechanical properties of composites by refining the reinforcements and matrix alloy.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"24 1","pages":"1555-1561"},"PeriodicalIF":0.0,"publicationDate":"2000-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85609307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-11-20DOI: 10.2320/MATERTRANS1989.41.1583
Y. Yokoyama, K. Fukaura, H. Sunada, K. Hiraga, A. Inoue
Phase relations between the liquid and the solid icosahedral (I-) phases were examined at different temperatures to determine the growth condition of a single Al-Cu-Fe I-quasicrystal using the Czochralski method. The composition of the single I-quasicrystal was chosen to be Al 64 Cu 23 Fe 13 due to the superior thermal stability. We found that the liquid composition, which equilibrates to the Al 64 Cu 23 Fe 13 I-phase at 1073 K, was Al 57.7 Cu 37.7 Fe 3.5 Si 1.1 . Based on the phase relation, production of a single Al 64 Cu 23 Fe 13 I-quasicrystal was attempted by using the Czochralski method. As a result, we succeeded in the growth of a single Al 64 Cu 23 Fe 13 I-quasicrystal, and we also measured the Vickers hardness of annealed single I-quasicrystal samples with different anneal times to estimate the structural improvement by annealing.
研究了液相和固相二十面体(I-)相在不同温度下的相关系，用Czochralski法测定了单个Al-Cu-Fe I准晶的生长条件。由于具有较好的热稳定性，单i准晶的组成选择为Al 64 Cu 23 Fe 13。结果表明，在1073 K时，液相组成为Al - 64 Cu - 23 Fe - 13 i相，为Al - 57.7 Cu - 37.7 Fe - 3.5 Si - 1.1。基于相关系，尝试用Czochralski法制备单个Al 64 Cu 23 Fe 13i准晶。结果，我们成功地生长出了单个Al - 64 Cu - 23 Fe - 13准晶，并测量了退火后不同退火次数的单个i -准晶样品的维氏硬度，以估计退火对结构的改善。
{"title":"Growth of a single Al64Cu23Fe13 icosahedral quasicrystal using the Czochralski method and annealing removal of strains","authors":"Y. Yokoyama, K. Fukaura, H. Sunada, K. Hiraga, A. Inoue","doi":"10.2320/MATERTRANS1989.41.1583","DOIUrl":"https://doi.org/10.2320/MATERTRANS1989.41.1583","url":null,"abstract":"Phase relations between the liquid and the solid icosahedral (I-) phases were examined at different temperatures to determine the growth condition of a single Al-Cu-Fe I-quasicrystal using the Czochralski method. The composition of the single I-quasicrystal was chosen to be Al 64 Cu 23 Fe 13 due to the superior thermal stability. We found that the liquid composition, which equilibrates to the Al 64 Cu 23 Fe 13 I-phase at 1073 K, was Al 57.7 Cu 37.7 Fe 3.5 Si 1.1 . Based on the phase relation, production of a single Al 64 Cu 23 Fe 13 I-quasicrystal was attempted by using the Czochralski method. As a result, we succeeded in the growth of a single Al 64 Cu 23 Fe 13 I-quasicrystal, and we also measured the Vickers hardness of annealed single I-quasicrystal samples with different anneal times to estimate the structural improvement by annealing.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"6 1","pages":"1583-1588"},"PeriodicalIF":0.0,"publicationDate":"2000-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72738047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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