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The research aims to analyze the impact that severe plastic deformation arising during Rotary Swaging has on mechanical properties and corrosion resistance of a near-a-titanium alloy Ti-2.5Al-2.6Zr (Russian industrial name PT7M). The nature of corrosion decay in fine-grained alloys caused by hot salt corrosion is known to vary from pit corrosion to intercrystalline corrosion at the onset of recrystallization processes. Resistance to hot salt corrosion in a fine-grained titanium alloy Ti-2.5Al-2.6Zr is shown to depend on the structural-phase state of grain boundaries that varies during their migration as a result of covering corrosive doping elements (aluminum, zirconium) distributed in the crystal lattice of a titanium alloy., Comment: 37 pages, 15 figures, 39 references

The results of investigations of the corrosion resistance of Al-Mg-Sc-Zr alloys with varying Mg content and different Sc/Zr ratios are presented. The objects of investigations were the Al-Mg-Sc-Zr alloys with total Sc + Zr content of 0.32 wt%. The concentration of Sc and Zr in the alloys varied with the increments of 0.02 wt%. The alloys were produced by induction casting. The effect of annealing temperature on the microhardness and electrical resistivity of the Al-Mg-Sc-Zr alloys was investigated. Corrosion tests were carried out in a medium simulating intergranular corrosion in aluminum alloys. Electrochemical studies and mass loss tests were performed. An increase in the Sc concentration and a decrease in the Zr one were shown to result in an increase in the corrosion rate. The primary Al3(ScxZr1-x) particles were found to have the main effect on the corrosion resistance of Al-Mg-Sc-Zr alloys. The dependence of the corrosion current on the annealing temperature of the Al-Mg-Sc-Zr alloy was found to have a non-monotonous character (with a maximum)., Comment: 29 pages, 2 tables, 11 figures, 58 references

Hot rolled commercial metastable austenitic steel 0.8C-18Cr-10Ni-0.1Ti (Russian industrial name 08X18H10T, analog 321L) with strongly elongated thin delta-ferrite particles in its microstructure was the object of investigations. The lengths of these delta-particles were up to 500 mkm, the thickness was 10 mkm. The formation of the strain-induced martensite as well as the grinding of the austenite and of the delta-ferrite grains take place during ECAP. During the annealing of the UFG steel, the formation of the delta-phase particles takes place. These particles affect the grain boundary migration and the strength of the steel. However, a reduction of the Hall-Petch coefficient as compared to the coarse-grained (CG) steel due to the fragmentation of the delta-ferrite particles was observed. The samples of the UFG steel were found to have 2-3 times higher stress relaxation resistance as compared to the CG steel (a higher macroelasticity stress and a lower stress relaxation magnitude). The differences in the stress relaxation resistance of the UFG and CG steels were investigated. ECAP was shown to result in an increase in the corrosion rate and in an increased tendency to the intergranular corrosion (IGC). The reduction of the corrosion resistance of the UFG steel was found to originate from the increase in the fraction of the strain-induced martensite during ECAP., Comment: 56 pages, 3 tables, 19 figures

We report resistivity and upper critical field B_c2(T) data for disordered (As deficient) LaO_0.9F_0.1FeAs_1-delta in a wide temperature and high field range up to 60 T. These samples exhibit a slightly enhanced superconducting transition at T_c = 28.5 K and a significantly enlarged slope dB_c2/dT = -5.4 T/K near T_c which contrasts with a flattening of B_c2(T) starting near 23 K above 30 T. The latter evidences Pauli limiting behaviour (PLB) with B_c2(0) approximately 63 T. We compare our results with B_c2(T)-data from the literature for clean and disordered samples. Whereas clean samples show almost no PLB for fields below 60 to 70 T, the hitherto unexplained pronounced flattening of B_c2(T) for applied fields H II ab observed for several disordered closely related systems is interpreted also as a manifestation of PLB. Consequences are discussed in terms of disorder effects within the frames of (un)conventional superconductivity, respectively., Comment: 2 pages, 3 figures, submitted to M2S Tokyo 09

High-quality superconducting LaFeAsO$_{1-x}$F$_{x}$ thin films were grown on single crystalline LaAlO$_{3}$ substrates with critical temperatures (onset) up to 28 K. Resistive measurements in high magnetic fields up to 40 T reveal a paramagnetically limited upper critical field, $\mu_{0}H_{c2}$(0) around 77 T and a remarkable steep slope of -7.5 T/K near $T_{c}$. From transport measurements we observed a weak link behavior in low magnetic fields and the evidence for a broad reversible regime., Comment: 4 pages, 4 figures, Phys. Rev. Lett. (accepted)

We report resistivity and upper critical field B_c2(T) data for As deficient LaO_(0.9)F_(0.1)FeAs_(1-delta) in a wide temperature and high field range up to 60 T. These disordered samples exhibit a slightly enhanced superconducting transition at T_c = 29 K and a significantly enlarged slope dB_(c2))/dT = -5.4 T/K near T_c which contrasts with a flattening of B_(c2)(T) starting near 23 K above 30 T. This flattening is interpreted as Pauli limiting behaviour (PLB) with B_(c2)(0) approx 63 T. We compare our results with B_(c2)(T)-data reported in the literature for clean and disordered samples. Whereas clean samples show no PLB for fields below 60 to 70 T, the hitherto unexplained flattening of B_(c2)(T) for applied fields H || ab observed for several disordered closely related systems is interpreted also as a manifestation of PLB. Consequences of our results are discussed in terms of disorder effects within the frame of conventional and unconventional superconductivity., Comment: 4 pages, 3 figures, submitted to RHMF09 (9th International Conference on the Research in High Magnetic Fields), Dresden, July 22-25, 2009

We report B_c2 data for LaO_{0.9}F_{0.1}FeAs_{1-delta} in a wide T and field range up to 60 Tesla. The large slope of B_c2 approx ~ -6 Tesla/K near an improved T_c = 28.5 K of the in-plane B_c2(T) contrasts with a flattening starting at 23 K above 30 Tesla we regard as the onset of Pauli-limited behavior (PLB) with B_c2(0) about 65 Tesla. We interpret a similar hitherto unexplained flattening of the B_c2(T) curves reported for at least three other disordered closely related systems as also as a manifestation of PLB. Their Maki parameters have been estimated analyzing their B_c2(T) data within the WHH approach. The pronounced PLB of (Ba,K)Fe_2As_2 single crystals from a tin-flux is attributed also to a significant As deficiency. Consequences of our results are discussed in terms of disorder effects within conventional (CSC) and unconventional superconductivity (USC). USC scenarios with nodes on individual Fermi surface sheets (FSS), can be discarded for our samples. The increase of dB_c2/dT|_{T_c} by sizeable disorder provides evidence for an important intraband (intra-FSS) contribution to the orbital upper critical field. We suggest that it can be ascribed either to an impurity driven transition from s_{+-} USC to CSC of an extended s_{++}-wave state or to a stabilized s_{+-}-state provided As-vacancies cause predominantly strong intraband scattering in the unitary limit. We compare our results with B_c2 data from the literature with no PLB for fields below 60 to 70 Tesla probed so far. A novel disorder related scenario of a complex interplay of SC with two different competing magnetic instabilities is suggested., Comment: 30 pages, 14 figures (1 removed, 1 added), discussions about s_{+-} superconductivity and the related interband scattering added, shortened version with a slightly changed title, references updated, two new authors added

We report upper critical field B_c2(T) data for disordered (arsenic-deficient) LaO_0.9F_0.1FeAs_(1-delta) in a wide temperature and magnetic field range up to 47 T. Because of the large linear slope of Bc2 about -5.4 T/K to -6.6 T/K near Tc = 28.5 K the T-dependence of the in-plane Bc2(T) shows a flattening near 23 K above 30 T which points to Pauli-limited behavior with Bc2(0) about 63-68 T. Our results are discussed in terms of disorder effects within conventional and unconventional superconducting pairings., Comment: Change of the title as suggested by the Editors, one author added, typos corrected, references updated, final published version

We report on a field-induced change of the electronic band structure of CeBiPt as evidenced by electrical-transport measurements in pulsed magnetic fields. Above ~25 T, the charge-carrier concentration increases nearly 30% with a concomitant disappearance of the Shubnikov-de Haas signal. These features are intimately related to the Ce 4f electrons since for the non-4f compound LaBiPt the Fermi surface remains unaffected. Electronic band-structure calculations point to a 4f-polarization-induced change of the Fermi-surface topology., Comment: 4 pages, 4 figures