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Using the bulk cementite samples produced by mechanical alloying and spark plasma sintering technique, high temperature deformation behaviors of cementite were studied. To avoid decomposition at high temperature, 5 at.% Mn alloyed cementite ((Fe0.95Mn0.05)3C) was mostly used. Brittle fracture was observed in the bulk cementite when deformed at a high strain rate at elevated temperatures (studied up to 1273 K). However, compression strain (this true strain larger than 2) was observed at around A1 temperature (1000 K) at stresses in the range of 100–150 MPa. Specimens were deformed without cracks and without change in hardness. After this superplastic flow, grains are slightly elongated and grain growth was observed. It was demonstrated that the bulk cementite sheets can be deformed cooperatively with low carbon steel sheets and fine layered cementite/low carbon steel laminates could be fabricated by superplastic deformation. As a possible deformation mechanism of lamellae cementite in pearlite, grain boundary sliding was proposed. [Copyright &y& Elsevier]

Abstract: A high strength Cu–NbC composite conductor for electrical applications was fabricated from Cu, Nb and C elemental powders using high pressure torsion (HPT). After HPT, samples showed close to full density (>99%). SEM observations revealed that atomic scale mixing occurred in the following order: deformation of Cu particles, the formation of Cu/Nb lamellar structure, fracturing of Nb lamella into sub-micron particles and the formation of uniform structure with fine distribution of Nb particles. The in situ formation of NbC in the copper matrix during HPT was detected. Annealing at 600 and 700°C resulted in substantial increases in microhardness and tensile strength and a slight decrease in electrical conductivity with increasing NbC volume fraction. The best combination of electrical conductivity (54% IACS) and tensile strength (810MPa) ever reported for such a composite was obtained in the Cu–2vol% NbC composite after annealing at 700°C. [Copyright &y& Elsevier]

Abstract: Deformation behavior of bulky cementite was investigated by compression, bending and tension tests at various temperatures and strain rates. Specimens of cementite {(Fe0.95Mn0.05)75C25} were prepared by plasma-sintering from a mixture of mechanically milled Fe, Mn and graphite powders. The maximum compressive strength observed was 3.2GPa at 573K. At room temperature, specimens exhibited brittle fracture under compression where the fracture strength was between 2 and 3GPa. At elevated temperatures under all types of loading modes, specimens showed high ductility, where grain boundary sliding was the dominant deformation mechanism because of the favorable grain size for superplasticity (less than 1.0μm). [Copyright &y& Elsevier]

Abstract: The abrasive wear property of single-phase cementite and cementite–iron composite, processed by mechanical alloying and spark plasma sintering, were investigated using a pin-abrasion test on fixed alumina abrasive grains. Single-phase cementite and cementite–iron composite had good wear resistances at applied pressures lower than 0.15MPa. However, at applied pressures higher than 0.31MPa, steels having a cementite volume fraction higher than 75% were intensely worn. In the former case, the wear mode of bulk cementite was ductile, and flow-type chips were observed on the worn surface. In the latter case, the wear mode was brittle, and brittle fracture chips were observed on the worn surface. [Copyright &y& Elsevier]