{"title":"Effect of impact damage on electrical resistivity of C/C - SiC composites","authors":"V. Srivastava, K. Maile, K. Bothe, A. Udoh","doi":"10.3139/146.030930","DOIUrl":"https://doi.org/10.3139/146.030930","url":null,"abstract":"Abstract The main objective of the present work was to study the low-velocity weight-drop impact damage behaviour of carbon– carbon silicon carbide (C/C–SiC) composites on electrical resistivity of the direct-current potential drop method. The results show that the electrical resistivity increases with increasing impact energy, which confirms that pre-microcracks of C/C–SiC composite grow very rapidly with a little amount of impact load and turn into a loss of conductivity of the material.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"8 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124689875","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":"Dry wear response of a Zn-based alloy containing 37.5 % Al as affected by sliding conditions","authors":"B. Prasad","doi":"10.3139/146.030897","DOIUrl":"https://doi.org/10.3139/146.030897","url":null,"abstract":"This paper discusses the observations made pertaining to dry sliding wear characteristics of a Zn-based alloy at different sliding speeds and pressures. The wear rate increased with speed and pressure. The wear rate versus pressure plots attained two slopes wherein the slope was low up to a specific pressure followed by an increased slope at still higher pressures. This trend was observed at all the sliding speeds except the maximum; in the latter case one slope (identical to that of the higher slope at the lower speeds) only was noted. The seizure pressure was noted to decrease with speed. The temperature near the specimen surface increased with test duration, pressure and sliding speed. The rate of temperature increase was significantly high initially. This was followed by a lower rate of increase in temperature at longer test durations. In some cases, the rate of temperature increase became high once again towards the end of the tests. The influence of applied pressure and sliding speed on the temperature increase was practically identical to that on wear rate. Lower wear rate of the alloy agreed with less surface/subsurface damage and finer debris formation and vice versa.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117087249","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":"The phase diagram of the Cd-In-Sn system","authors":"E. Dichi, B. Legendre","doi":"10.3139/146.030827","DOIUrl":"https://doi.org/10.3139/146.030827","url":null,"abstract":"Abstract The phase diagram of the Cd–In–Sn ternary system was studied by X-ray powder diffraction analysis and differential scanning calorimetry. 138 alloys were elaborated on nine vertical sections. Three transition peritectic reactions (U-type), two ternary eutectoid reactions (E-type) and one ternary eutectic reaction (E-type) were characterized.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122195431","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}
D. Fátay, E. Bastarash, K. Nyilas, S. Dobatkin, J. Gubicza, T. Ungár
{"title":"X-ray diffraction study on the microstructure of an Al-Mg-Sc-Zr alloy deformed by high-pressure torsion","authors":"D. Fátay, E. Bastarash, K. Nyilas, S. Dobatkin, J. Gubicza, T. Ungár","doi":"10.3139/146.030842","DOIUrl":"https://doi.org/10.3139/146.030842","url":null,"abstract":"The microstructure and thermal stability of plastically deformed Al-5.9Mg-0.3Sc-0.18Zr alloy have been investigated. Severe plastic deformation has been performed by high-pressure torsion (HPT) straining at room temperature. The microstructure as a function of the number of rotations is studied by X-ray diffraction peak profile analysis. It is concluded that the HPT technique results in a nanostructure with about 40 nm crystallite size. The crystallite size first decreases with the number of rotations, however, after five turns it reaches saturation. The dislocation density increases with turns and the character of the dislocations becomes more edge type. The thermal stability of the nanostructure is studied by differential scanning calorimetry. The stored energy increases with the number of rotations and the maximum of the exothermal peak was shifted to higher temperatures. Increasing the temperature of the heat treatment, the dislocation density decreases faster than the increase of the mean crystallite size.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132930025","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}
T. Scholz, M. May, M. Swain, G. Schneider, N. Claussen
{"title":"Nanoindentation measurements on infiltrated alumina-aluminide alloys","authors":"T. Scholz, M. May, M. Swain, G. Schneider, N. Claussen","doi":"10.3139/146.030819","DOIUrl":"https://doi.org/10.3139/146.030819","url":null,"abstract":"Abstract Metal–ceramic composites have been fabricated by reactive infiltration with a laboratory squeeze caster. Two types of these composites are characterised by nanoindentation. While the first one contains Al2O3, TiO2 and Al, the second one contains Al2O3, TiAl3 as the main products and a little Ti5Si3. The phases of the second specimen are formed during infiltration. Hardness and Young's modulus values in both composites were compared with measurements of the bulk material of each phase. A significant depth dependence of the properties was detected in the composite materials and simulated by a finite element analysis. The measured values agreed well with the simulation.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"252 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134497120","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":"Dislocation microstructures of single crystal 〈001〉 CMSX-4 specimens tensile tested at 700 and 1000°C","authors":"F. Schubert, H. Penkalla, L. Singheiser","doi":"10.3139/146.030705","DOIUrl":"https://doi.org/10.3139/146.030705","url":null,"abstract":"Abstract Two principal methods are used to derive constitutive equations for single crystal Ni-base superalloys: development of a creep potential according the Hill's theory and the summarization of all activated slip systems: theoretically, the octahedral and the cubic slip system must be considered. An overview of dislocation structure evolution has been performed using transmission electron microscopy (TEM) techniques on 〈001〉-orientated CMSX-4 specimens after tensile tests. The aim of the applied conventional TEM methods was to provide with more details about the influence of temperature and deformation rate on the deformation behaviour of CMSX-4 nickel-base single crystal. A correlation of the γ′ phase deformation mechanisms and associated mechanical responses for different tensile testing conditions has been done. With TEM methods the dislocation dipole identification as well as the stacking fault nature has been demonstrated.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"289 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133600151","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":"Reaktionssintern von AlMg-MgO zur Herstellung von Bauteilen auf Spinellbasis","authors":"S. Dierkes, M. Kuntz, G. Grathwohl","doi":"10.3139/146.030761","DOIUrl":"https://doi.org/10.3139/146.030761","url":null,"abstract":"Abstract A new process for the production of spinel-based materials by reaction sintering is presented. Oxidation of aluminum is accelerated by using magnesium as an alloying element as well as by the contact to magnesia. Thus, the composition used here leads to a maximum of the reaction kinetics. The effects occurring during the oxidation process have to be properly controlled, in particular the time of wetting of magnesia by molten aluminum. The reaction can be completed at low temperatures (900–1000°C). The fairly microstructure is characterised by a closed porosity, leading to a gastight material. There is only very little volume change during reaction sintering, qualifying the material e. g. for assembling with metallic or ceramic components.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130285099","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":"Deformation and fracture of Nb/α-Al2O3 composites in compression and bending studied by an optical method","authors":"Y. Liu, C. Kohnle, D. Brunner, M. Rühle","doi":"10.3139/146.030694","DOIUrl":"https://doi.org/10.3139/146.030694","url":null,"abstract":"Abstract The fracture behavior of Nb/a-Al2O3 composites was investigated both in compression tests and bending tests using an optical full-field method for the observation of strain fields on the metal surfaces. Joints of polycrystalline materials were prepared by high-vacuum diffusion bonding. The building up of the strain near the interface during the tests, finally leading to the fracture, was studied by examining the strain and displacement fields of the whole metal layer. In compression tests, two types of fracture, fracture of alumina and fracture of interfaces, were detected by cross-examination of the stress–strain curve and the strain maps. The fracture of alumina in compression tests was influenced by the Nb layer thickness and can be rationalized by an extension of Cottrell's model. For four-point bending tests, the results of the strain maps, determined experimentally by means of the optical method, confirmed the strain maps resulting from finite element simulations.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126101215","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":"Precipitation of β-phase and twinning during deformation of Mg–Al alloy AZ91 at 150°C after solution treatment","authors":"P. Zhang, W. Blum","doi":"10.3139/146.030716","DOIUrl":"https://doi.org/10.3139/146.030716","url":null,"abstract":"Abstract Precipitation of β-phase and deformation twinning have been studied in a solid solution-treated AZ91 alloy, which was subjected to compressive creep loading at 150°C and 100 MPa for 163 h. It was found that nucleation of β-phase in solution-treated AZ91 is enhanced by concurrent deformation under creep conditions at 150°C. The relatively fine precipitate structure leads to a reduction in minimum creep rate and, therefore, to an increase in creep life by a factor of 10 compared to the as-cast condition at the investigated conditions. In addition, twinning occurred in coarse grains of hard orientation. The twin boundaries lead to formation of incoherent precipitates and discontinuous precipitation within the former grains.","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133927213","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}
Michael Vogel, O. Kraft, P. Staron, H. Clemens, R. Rauh, E. Arzt
{"title":"Microstructure of die-cast alloys Mg-Zn-Al(-Ca): A study by electron microscopy and small-angle neutron scattering","authors":"Michael Vogel, O. Kraft, P. Staron, H. Clemens, R. Rauh, E. Arzt","doi":"10.3139/146.030564","DOIUrl":"https://doi.org/10.3139/146.030564","url":null,"abstract":"Abstract The microstructure of a magnesium die-cast alloy with 8 wt.% Zn and 5 wt.% Al (ZA85) and of two alloy modifications with 0.3 and 0.9 wt.% Ca (ZACa8503 and ZACa8509) are compared. Optical, scanning electron and transmission electron microscopy (TEM) were used to study the microstructure in as-cast and annealed conditions. Small-angle neutron scattering (SANS) measurements were carried out to characterize the early stages of the precipitation process. The die-cast microstructure of ZA85, ZACa8503 and ZACa8509 consists of dendritic α-Mg grains and coarse intermetallic grain-boundary phases. In the Ca-free ZA85 alloy, grain boundaries are decorated with a quasi-crystalline phase with icosahedral point-group symmetry (I phase), a metastable modification of the equilibrium τ phase (Mg32(Al, Zn)49). At the grain boundaries of the Ca-containing ZA85 alloys, small amounts of the stable cubic τ phase Mg32(Al, Zn, Ca)49 as well as Al2(Ca, Zn) phase, were detected in addition to the I phase. In the as-cast c...","PeriodicalId":301412,"journal":{"name":"Zeitschrift Fur Metallkunde","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123574598","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}