Borchers, Christine

[["dc.bibliographiccitation.firstpage","48"],["dc.bibliographiccitation.journal","Scripta Materialia"],["dc.bibliographiccitation.lastpage","51"],["dc.bibliographiccitation.volume","98"],["dc.contributor.author","Chen, Y. Z."],["dc.contributor.author","Ma, X. Y."],["dc.contributor.author","Shi, X. H."],["dc.contributor.author","Suo, T."],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Zhang, Kunhua"],["dc.contributor.author","Liu, F."],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T09:59:40Z"],["dc.date.available","2018-11-07T09:59:40Z"],["dc.date.issued","2015"],["dc.description.abstract","Well-annealed Pd and Pd-H alloys were subjected to tensile tests. It is found that the presence of H does not affect the yield strength but enhances the strain hardening of Pd remarkably. This is explained by a negligible solute drag effect of H on the movement of dislocations, and by H-induced enhanced multiplication of dislocations upon plastic deformation, respectively. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.scriptamat.2014.11.012"],["dc.identifier.isi","000348965500013"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/37648"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1359-6462"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Hardening effects in plastically deformed Pd with the addition of H"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","726"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science"],["dc.bibliographiccitation.lastpage","738"],["dc.bibliographiccitation.volume","47A"],["dc.contributor.author","Chen, Y. Z."],["dc.contributor.author","Csiszar, G."],["dc.contributor.author","Cizek, Jakub"],["dc.contributor.author","Shi, X. H."],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Li, Y. J."],["dc.contributor.author","Liu, F."],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T10:18:59Z"],["dc.date.available","2018-11-07T10:18:59Z"],["dc.date.issued","2016"],["dc.description.abstract","Cold-drawn pearlitic steel wires with a drawing true strain of 3 were annealed at temperatures (T (ann)) ranging from 423 K to 723 K (150 A degrees C to 450 A degrees C) with an interval of 50 K. Recovery of the lattice defects in the severely deformed ferrite lamellae were characterized by means of high-energy X-ray diffraction and positron annihilation techniques (including positron annihilation spectroscopy and coincidence Doppler broadening spectroscopy). Accordingly, the impact of defect recovery on the softening of the annealed wires was investigated. It is found that at low temperatures [T (ann) a parts per thousand currency sign 523 K (250 A degrees C)], the recovery of the lattice defects in ferrite lamellae is dominated by the agglomeration and annihilation of vacancy clusters, while at T (ann) > 523 K (250 A degrees C), the recovery process is controlled by the annihilation of dislocations. Further analyses on the softening of the annealed wires indicate that the evolutions of dislocation density and concentration of vacancy clusters, and the strain age hardening in ferrite lamellae play important roles in changing the strength of the wires. The strain aging hardening leads to a maximum strength at 473 K (150 A degrees C). Above 523 K (250 A degrees C), the annihilations of vacancy clusters and dislocations in ferrite lamellae cause a continuous softening of the wires, where the decrease in dislocation density plays a major role."],["dc.identifier.doi","10.1007/s11661-015-3263-z"],["dc.identifier.isi","000368062300010"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/41565"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1543-1940"],["dc.relation.issn","1073-5623"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Defect Recovery in Severely Deformed Ferrite Lamellae During Annealing and Its Impact on the Softening of Cold-Drawn Pearlitic Steel Wires"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","390"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Scripta Materialia"],["dc.bibliographiccitation.lastpage","393"],["dc.bibliographiccitation.volume","64"],["dc.contributor.author","Chen, Y. Z."],["dc.contributor.author","Csiszar, G."],["dc.contributor.author","Cizek, Jakub"],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Ungar, T."],["dc.contributor.author","Goto, S."],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T08:58:58Z"],["dc.date.available","2018-11-07T08:58:58Z"],["dc.date.issued","2011"],["dc.description.abstract","Cold-drawn pearlitic steel wires are widely used in numerous engineering fields. Combining X-ray line profile analysis and positron annihilation spectroscopy methods, up to 10(-5)-10(-4) vacancies were found in a-ferrite of a cold-drawn pearlitic steel wire with a true strain of epsilon = 3. The formation of deformation-induced vacancies in alpha-ferrite of cold-drawn pearlitic steel wire was quantitatively testified. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.scriptamat.2010.10.039"],["dc.identifier.isi","000286540700007"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/23775"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1359-6462"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","On the formation of vacancies in alpha-ferrite of a heavily cold-drawn pearlitic steel wire"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3172"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Acta Materialia"],["dc.bibliographiccitation.lastpage","3185"],["dc.bibliographiccitation.volume","61"],["dc.contributor.author","Chen, Y. Z."],["dc.contributor.author","Herz, A."],["dc.contributor.author","Li, Y. J."],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Choi, P."],["dc.contributor.author","Raabe, Dierk"],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T09:25:10Z"],["dc.date.available","2018-11-07T09:25:10Z"],["dc.date.issued","2013"],["dc.description.abstract","A series of nanocrystalline Fe-C alloys with different carbon concentrations (x(tot)) up to 19.4 at.% (4.90 wt.%) are prepared by ball milling. The microstructures of these alloys are characterized by transmission electron microscopy and X-ray diffraction, and partitioning of carbon between grain boundaries and grain interiors is determined by atom probe tomography. It is found that the segregation of carbon to grain boundaries of alpha-ferrite can significantly reduce its grain size to a few nanometers. When the grain boundaries of ferrite are saturated with carbon, a metastable thermodynamic equilibrium between the matrix and the grain boundaries is approached, inducing a decreasing grain size with increasing x(tot). Eventually the size reaches a lower limit of about 6 nm in alloys with x(tot) > 6.19 at.% (1.40 wt.%); a further increase in x(tot) leads to the precipitation of carbon as Fe3C. The observed presence of an amorphous structure in 19.4 at.% C (4.90 wt.%) alloy is ascribed to a deformation-driven amorphization of Fe3C by severe plastic deformation. By measuring the temperature dependence of the grain size for an alloy with 1.77 at.% C additional evidence is provided for a metastable equilibrium reached in the nanocrystalline alloy. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.actamat.2013.02.006"],["dc.identifier.isi","000318533500004"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30000"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1359-6454"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Nanocrystalline Fe-C alloys produced by ball milling of iron and graphite"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","24"],["dc.bibliographiccitation.journal","Acta Materialia"],["dc.bibliographiccitation.lastpage","34"],["dc.bibliographiccitation.volume","115"],["dc.contributor.author","Tiegel, Marie C."],["dc.contributor.author","Martin, May L."],["dc.contributor.author","Lehmberg, Annegret K."],["dc.contributor.author","Deutges, Martin"],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T10:10:10Z"],["dc.date.available","2018-11-07T10:10:10Z"],["dc.date.issued","2016"],["dc.description.abstract","Purified iron was loaded electrochemically with hydrogen in the presence of a hydrogen promoter, leading to the formation of cracks inside of the bulk and blisters on the surface. The mechanism for the crack initiation was investigated using SEM cross-section images and by investigating the fracture surface of a ruptured sample, where preexisting cracks were exposed for observation. Cracks were found to originate at inclusions. It was observed that blisters grow with time, leading to the conclusion that the underlying growth process is discontinuous. The surface morphology of the blisters consists of steps and in the underlying microstructure investigated by TEM shear bands were found. Hydrogen gas pressures in the range of half of the yield strength of iron were determined directly after hydrogen loading using density measurements. Therefore, the hydrogen gas pressure in the cracks was concluded to be the driving force for crack advance. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.actamat.2016.05.034"],["dc.identifier.isi","000380083400003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/39804"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1873-2453"],["dc.relation.issn","1359-6454"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Crack and blister initiation and growth in purified iron due to hydrogen loading"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","690"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Scripta Materialia"],["dc.bibliographiccitation.lastpage","693"],["dc.bibliographiccitation.volume","69"],["dc.contributor.author","Kresse, T."],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T09:18:22Z"],["dc.date.available","2018-11-07T09:18:22Z"],["dc.date.issued","2013"],["dc.description.abstract","Self-diffusion in face-centered cubic (fcc) iron and hexagonal close-packed cobalt as well as Ni diffusion in bcc iron and Co-diffusion in fcc nickel are all accelerated in the presence of dissolved carbon. This is attributed to an enlarged vacancy concentration due to an attractive vacancy carbon interaction. The enlarged Ni diffusion in body-centered cubic (bcc) iron contradicts conclusions for self-diffusion in bcc iron obtained from first-principles calculations. This discrepancy is discussed in the present study. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft [KI230/34, SFB 602, TP B13]"],["dc.identifier.doi","10.1016/j.scriptamat.2013.08.001"],["dc.identifier.isi","000325194500012"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/28397"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1359-6462"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Vacancy-carbon complexes in bcc iron: Correlation between carbon content, vacancy concentration and diffusion coefficient"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","424"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Scripta Materialia"],["dc.bibliographiccitation.lastpage","427"],["dc.bibliographiccitation.volume","69"],["dc.contributor.author","Kresse, T."],["dc.contributor.author","Li, Y. J."],["dc.contributor.author","Boll, Torben"],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Choi, P."],["dc.contributor.author","Al-Kassab, Talaat"],["dc.contributor.author","Raabe, Dierk"],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T09:21:04Z"],["dc.date.available","2018-11-07T09:21:04Z"],["dc.date.issued","2013"],["dc.description.abstract","In patented and cold-drawn pearlitic steel wires dissociation of cementite occurs during mechanical deformation. In this study the influence of the carbon decomposition on the diffusion of nickel in ferrite is investigated by means of atom probe tomography. In the temperature range 423-523 K we observed a much smaller activation energy of Ni diffusion than for self-diffusion in body-centered cubic iron, indicating an increased vacancy density owing to enhanced formation of vacancy carbon complexes. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft [SFB 602, TP B13]; KAUST baseline funds"],["dc.identifier.doi","10.1016/j.scriptamat.2013.05.039"],["dc.identifier.isi","000322416500021"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/29028"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1359-6462"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Influence of supersaturated carbon on the diffusion of Ni in ferrite determined by atom probe tomography"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","17"],["dc.bibliographiccitation.journal","Scripta Materialia"],["dc.bibliographiccitation.lastpage","19"],["dc.bibliographiccitation.volume","86"],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Lehmberg, Annegret K."],["dc.contributor.author","Deutges, M."],["dc.contributor.author","Cizek, Jakub"],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T09:36:23Z"],["dc.date.available","2018-11-07T09:36:23Z"],["dc.date.issued","2014"],["dc.description.abstract","Cold-drawn pearlitic steel wires were subjected to differential scanning calorimetry and resistivity measurements during heating. Both techniques yield two peaks, one at 500-600 K, the other at 400-450 K. Whereas the peak at 500-600 K can be ascribed to voids consisting of about 10 vacancies as confirmed by positron annihilation spectroscopy, the low-temperature peak is ascribed to V1C2 and/or V2C4 complexes. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.scriptamat.2014.04.016"],["dc.identifier.isi","000339038400005"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/32605"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1359-6462"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Effect of annealing on point defect population in cold-drawn pearlitic steel wires"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","233"],["dc.bibliographiccitation.journal","Ultramicroscopy"],["dc.bibliographiccitation.lastpage","238"],["dc.bibliographiccitation.volume","132"],["dc.contributor.author","Li, Y. J."],["dc.contributor.author","Choi, P."],["dc.contributor.author","Goto, S."],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Raabe, Dierk"],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T09:20:40Z"],["dc.date.available","2018-11-07T09:20:40Z"],["dc.date.issued","2013"],["dc.description.abstract","A local electrode atom probe has been employed to analyze the redistribution of alloying elements including Si, Mn, and Cr in pearlitic steel wires upon cold-drawing and subsequent annealing It has been found that the three elements undergo mechanical mixing upon cold-drawing at large strains, where Mn and Cr exhibit a nearly homogeneous distribution throughout both ferrite and cementite, whereas Si only dissolves slightly in cementite. Annealing at elevated temperatures leads to a reversion of the mechanical alloying. Si atoms mainly segregate at well-defined ferrite (sub)grain boundaries formed during annealing. Cr and Mn are strongly concentrated in cementite adjacent to the ferrite/cementite interface due to their lower diffusivities in cementite than in ferrite. (C) 2012 Elsevier B.V. All rights reserved."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft [SFB 602, KI230/34-1]"],["dc.identifier.doi","10.1016/j.ultramic.2012.10.010"],["dc.identifier.isi","000324235500038"],["dc.identifier.pmid","23237772"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/28932"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.publisher.place","Amsterdam"],["dc.relation.eventlocation","Tuscaloosa, AL"],["dc.relation.eventstart","2012-05"],["dc.relation.issn","1879-2723"],["dc.relation.issn","0304-3991"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Atomic scale investigation of redistribution of alloying elements in pearlitic steel wires upon cold-drawing and annealing"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3965"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Acta Materialia"],["dc.bibliographiccitation.lastpage","3977"],["dc.bibliographiccitation.volume","59"],["dc.contributor.author","Li, Y. J."],["dc.contributor.author","Choi, P."],["dc.contributor.author","Borchers, Christine"],["dc.contributor.author","Westerkamp, S."],["dc.contributor.author","Goto, S."],["dc.contributor.author","Raabe, Dierk"],["dc.contributor.author","Kirchheim, Reiner"],["dc.date.accessioned","2018-11-07T08:55:31Z"],["dc.date.available","2018-11-07T08:55:31Z"],["dc.date.issued","2011"],["dc.description.abstract","Pearlitic steel can exhibit tensile strengths higher than 5 GPa after severe plastic deformation, where the deformation promotes a refinement of the lamellar structure and cementite decomposition. However, a convincing correlation between deformation and cementite decomposition in pearlite is still absent. In the present work, a local electrode atom probe was used to characterize the microstructural evolution of pearlitic steel, cold-drawn with progressive strains up to 5.4. Transmission electron microscopy was also employed to perform complementary analyses of the microstructure. Both methods yielded consistent results. The overall carbon content in the detected volumes as well as the carbon concentrations in ferrite and cementite were measured by atom probe. In addition, the thickness of the cementite filaments was determined. In ferrite, we found a correlation of carbon concentration with the strain, and in cementite, we found a correlation of carbon concentration with the lamella thickness. Direct evidence for the formation of cell/subgrain boundaries in ferrite and segregation of carbon atoms at these defects was found. Based on these findings, the mechanisms of cementite decomposition are discussed in terms of carbon-dislocation interaction. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft [SFB 602]"],["dc.identifier.doi","10.1016/j.actamat.2011.03.022"],["dc.identifier.isi","000291119700020"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/22927"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1359-6454"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Atomic-scale mechanisms of deformation-induced cementite decomposition in pearlite"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]