Scripta Metallurgica et Materialia最新文献

{"title":"Nanocomposite R2Fe14B/α-Fe and Sm2 (Fe-Ga)17Cx/α-Fe magnets","authors":"L. Withanawasam ∗,&nbsp;Y.H. Zheng,&nbsp;G.C. Hadjipanayis,&nbsp;R.F. Krause","doi":"10.1016/0956-716X(95)00426-V","DOIUrl":"10.1016/0956-716X(95)00426-V","url":null,"abstract":"<div><p>We have studied the crystallization, crystal structure, microstructure, and magnetic properties of melt-spun ribbons of R₆(Fe-Nb)₈₈B₆ with RNd, Pr, Dy, Tb and Nd_3.5(Fe-Nb)₉₃B_3.5 consisting of a mixture of exchange-coupled magnetically hard R₂Fe₁₄B and soft α-Fe phases. The as-spun ribbons of R-rich composition crystallize in two steps; for RNd, Pr, and Dy at first the Y₃Fe₆₂B₁₄-type + α-Fe phases and subsequently they transform to 2:14:1 and α-Fe upon heating above 700 °C. The intermediate phase in the case of Tb₆(Fe-Nb)₈₈B₆ is of the TbCu₇-type. Very high remanences up to 145 emu/g with reduced remanences ranging from 0.6 to 0.7 were observed. The coercivity of the samples was found to vary with the R element and the hard phase content. The highest room temperature coercivity of 4.5 kOe was obtained in a Nd₄Tb₂(Fe-Nb)₈₈B₆ sample. The observed reversible demagnetization curves are characteristic of exchange-spring magnets.</p><p>A two-phase microstructure was also obtained in Sm-Fe-Ga-C ribbons consisting of exchange-coupled 2:17 and α-Fe phases after annealing in the temperature range of 700–800 °C. The highest coercive force (12.8 kOe) was obtained in samples annealed at 800 °C. Annealing at 700 °C led to finer grains with lower coercivities (5kOe) but higher remanences.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1765-1774"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00426-V","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75496166","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}

{"title":"Correlation between magnetic properties and phase-separated microstructure of electroless CoNiP perpendicular magnetic recording media","authors":"T. Homma ,&nbsp;T. Osaka ,&nbsp;Y. Yamazaki ,&nbsp;T. Namikawa","doi":"10.1016/0956-716X(95)00414-Q","DOIUrl":"10.1016/0956-716X(95)00414-Q","url":null,"abstract":"<div><p>Correlation between magnetic and structural properties of electroless-deposited CoNiP films for the use of perpendicular magnetic recording media was studied, focusing upon their phase-separated structure in nanometer scale. The media with various perpendicular coercivity, Hc(⊥), were examined and it was clarified that higher Hc(⊥) medium showed a clearer phase-separated condition, which was confirmed by the selective chemical-etching technique. It was strongly indicated that such a structure plays an important role in attaining a high Hc(⊥) and in forming an hcp structure in a film with a Ni-rich average composition.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1569-1573"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00414-Q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79988940","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}

{"title":"Magnetic and structural properties of high coercivity nanocrystalline CoSm films with in-plane anisotropy","authors":"D.J. Sellmyer,&nbsp;Z.S. Shan,&nbsp;Y. Liu,&nbsp;S.H. Liou,&nbsp;S.S. Malhotra,&nbsp;B.W. Robertson","doi":"10.1016/0956-716X(95)00430-4","DOIUrl":"10.1016/0956-716X(95)00430-4","url":null,"abstract":"<div><p>This paper presents results and an overview of magnetic and nanostructural properties of CoSm alloys which have high potential for future ultra high-density longitudinal magnetic recording. These sputtered films consist of about 5 nm crystallites embedded in an amorphous matrix, with the easy axes of the nanocrystallites in the film plane. The films have high coercivities, 3–4 kOe, and other highly favorable properties. Fundamental aspects of the relationship between nanostructure and magnetic properties are discussed.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1545-1552"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00430-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83378239","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}

{"title":"Influence of Cr addition on the magnetic softness of nanocrystalline FeCuNbSiB alloys","authors":"J. González,&nbsp;N. Murillo,&nbsp;I. Mondragón,&nbsp;J.M. Blanco,&nbsp;J. Echeberría,&nbsp;E. González,&nbsp;J.M. González","doi":"10.1016/0956-716X(95)00408-N","DOIUrl":"10.1016/0956-716X(95)00408-N","url":null,"abstract":"<div><p>The compositional dependence of the effective anisotropy of as-quenched and thermally treated, Cr substituted FeCuNbSiB melt spun samples, is examined through the results corresponding to the measurement of the transverse biased initial susceptibility. The analysis of these experimental data allowed us to evidence the occurrence of magnetization ripple and to evaluate the evolution with the thermal treatments of the so-called dispersion field and of the dimensions of the coupled magnetization regions underlying the measured values of the effective anisotropy. It is concluded that magnetostatic interactions play (in addition to exchange interactions) a major role on the formation of these coupled regions.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1757-1764"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00408-N","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82750809","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}

{"title":"Thin film structures for low field granular giant magnetoresistance","authors":"Kevin R. Coffey,&nbsp;Todd L. Hylton,&nbsp;Michael A. Parker,&nbsp;J.Kent Howard","doi":"10.1016/0956-716X(95)00390-H","DOIUrl":"10.1016/0956-716X(95)00390-H","url":null,"abstract":"<div><p>Giant magnetoresistance (GMR) is a relatively new field of study pursued by scientists and technologists alike. A potential application of GMR thin films is the replacement of NiFe alloy thin films (having anisotropic magnetoresistance) to obtain greater signal. Applications of this type require that the GMR be obtained at low fields, on the order of 10 Oe. In this paper three types of granular GMR thin film structures are described: co-deposited heterogeneous alloys, granular bi-layers, and discontinuous multilayers. Experimental examples of each type are presented, and the field dependence of GMR for each structure is discussed. Only discontinuous multilayer thin film structures have shown suitable GMR at low fields, and the properties and microstructure of these thin films will be described in greater detail.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1593-1602"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00390-H","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77638188","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}

{"title":"Permanent magnets — New microstructural aspects","authors":"Josef Fidler,&nbsp;Johannes Bernardi,&nbsp;Thomas Schrefl","doi":"10.1016/0956-716X(95)00392-9","DOIUrl":"10.1016/0956-716X(95)00392-9","url":null,"abstract":"<div><p>The influence of the microstructure on the hard magnetic properties of rare earth-iron based magnetic materials with outstanding coercivities and energy density products is surveyed. Nd₂Fe₁₄B based permanent magnets exhibit a complex multiphase microstructure. The grain size of the magnets strongly depends on the processing technique. If dopant and substituent elements are added to conventional magnets, the coercivity is mostly increased and the remanence slightly decreased. Substituent elements such as Dy or Co mainly change the magnetocrystalline anisotropy and Curie temperature of the hard magnetic Nd₂Fe₁₄B-phase. Our systematical TEM-study shows that the dopants, because of their different effect on the microstructure, can be divided into two groups independently of the processing technique, each with similar microstructural features. Secondary phases in the form of precipitates or new intergranular phases are formed after the dotation. Both types of dopants partly increase the coercivity or improve corrosion resistance. If a combination of type 1 and type 2 dopant elements to Nd-Fe-B or (Nd,Dy)-(Fe,Co)-B magnets is chosen, the coercivity and corrosion resistance is considerably improved. Magnets of the type Nd-Fe-B:(Ga,Nb), Nd-Fe-B:(Cu,Nb), Nd-(Fe,Co)-B:(Al,Mo) and (Nd,Dy)-(Fe,Co)-B:(Al,V) were systematically investigated and were found to behave according to the microstructural predictions. Secondary, soft magnetic phases, such as α-Fe, play an important role in the new, composite type hard magnetic materials. Our numerical, finite element comparison of the coercivity and remanence enhancement of nanocrystalline Nd₂Fe₁₄B and Sm₂Fe₁₇N_2.7 isotropic magnets show that the dipolar and exchange interactions between the hard and soft magnetic grains control the exchange hardening. The remanence and the coercivity of exchange hardened, nanocrystalline, hard magnets sensitively depend on microstructural features, such as the grain size and the volume fraction of the soft magnetic phase.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1781-1791"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00392-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80975746","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}

{"title":"Anisotropy, exchange coupling and phase transition in bilayer systems","authors":"Xiao Hu,&nbsp;Yoshiyuki Kawazoe","doi":"10.1016/0956-716X(95)00429-Y","DOIUrl":"10.1016/0956-716X(95)00429-Y","url":null,"abstract":"<div><p>Phase transitions in magnetic multilayer structures are studied with mean-field theory. Transitions between different magnetization configurations in bilayer systems with different anisotropies are discussed by means of variational method. The responsible mechanism is the competition between the anisotropy energy and the exchange coupling. The para-ferro magnetic phase transition in a ferromagnetic bilayer system is investigated with the Ginzburg-Landau theory. The effect of finiteness of the layer thickness has been revealed. Critical phenomena according to the variance of the layer thickness are clarified.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1841-1847"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00429-Y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89044099","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}

{"title":"On the nitrogen occupation in the Y2Fe17 lattice","authors":"Y.D. Zhang ,&nbsp;D.P. Yang ,&nbsp;J.I. Budnick ,&nbsp;W.A. Hines ,&nbsp;W.Q. Xu ,&nbsp;N.X. Shen ,&nbsp;D.M. Pease ,&nbsp;W.G. Fernando ,&nbsp;T.D. Xiao","doi":"10.1016/0956-716X(95)00406-L","DOIUrl":"10.1016/0956-716X(95)00406-L","url":null,"abstract":"","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1817-1824"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00406-L","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76063577","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}

{"title":"Micromagnetic and microstructural studies of NdFeB by TEM","authors":"J.N. Chapman,&nbsp;L.J. Heyderman,&nbsp;S. Young,&nbsp;D.M. Donnet,&nbsp;P.Z. Zhang ,&nbsp;H.A. Davies","doi":"10.1016/0956-716X(95)00418-U","DOIUrl":"10.1016/0956-716X(95)00418-U","url":null,"abstract":"<div><p>Transmission electron microscopy has been used to study the magnetic and physical microstructure of thinned samples of NdFeB. Various compositions of sintered material and nanocrystalline melt-spun ribbon have been studied. The mean grain size in the materials ranges from 3 μm in the sintered material down to 20nm in the ribbon and this has a pronounced effect on the domain structures supported. Details of the magnetisation distribution both within grains and around boundaries are given and these are discussed in terms of the observed bulk magnetic properties.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1807-1816"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00418-U","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77266512","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}

{"title":"Magnetic properties of mechanically alloyed Fe-Ni-Ag","authors":"L.H. Bennett ,&nbsp;L. Takacs ,&nbsp;L.J. Swartzendruber ,&nbsp;J. Weissmüller ,&nbsp;L.A. Bendersky ,&nbsp;A.J. Shapiro","doi":"10.1016/0956-716X(95)00456-6","DOIUrl":"10.1016/0956-716X(95)00456-6","url":null,"abstract":"<div><p>We have prepared mechanically alloyed samples of FeNi, FeNi₃, and (FeNi₃)_{1 − x}Ag_x. The production of nanometer size grains was confirmed by x-ray broadening and electron microscopy. X-ray measurements indicated that a small amount (~7%) of Ag could be alloyed into the Fe-Ni and that considerable lattice strain was present. Mössbauer and magnetic measurements found no evidence for superparamagnetism in these alloys.</p></div>","PeriodicalId":101150,"journal":{"name":"Scripta Metallurgica et Materialia","volume":"33 10","pages":"Pages 1717-1724"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0956-716X(95)00456-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81272327","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}