Quantitative microstructural characterisation of Fe–30Ni alloy after martensitic transformations by means of stereological and magnetic methods

In the Fe–30Ni alloy investigated a martensitic transformation can occur both during quenching or plastic deformation. Martensite formed during plastic deformation, depending on the thermo-mechanical treatment applied, exhibits a different morphology from that achieved during quenching and forms the so-called composite-like structure. The morphology and volume fraction of martensite depends both on strain and temperature. In the present studies Fe–30Ni alloy was deformed by monotonic rolling in one path and perpendicular rolling in the temperature range M_D–M_S. The aim of the investigations was a determination of martensite volume fraction depending on the strain and temperature. To examine the influence of strain, the alloy was deformed by rolling in one path or perpendicular rolling at a temperature of − 30 °C, in the strain range of 10–30%. The dependence of temperature was investigated by rolling with 30% strain in a temperature range from − 30 °C to − 80 °C. The variants of thermo-mechanical treatment performed enabled us to achieve different martensite morphologies and volume fractions. Microstructural analysis was performed by means of light microscopy and transmission electron microscopy. The results of quantitative microstructural analysis of martensite and retained austenite volume fractions formed in different thermo-mechanical treatments were compared with those obtained by magnetic measurements. The fraction of deformation-induced martensite determined varied from 2% to 86%. The partial volume fractions V_V^MF of martensite formed in different deformation directions were also determined. It was found that the influence of the temperature on the martensite volume fraction is more pronounced than the influence of strain.     

Rehabilitation after aortic valve replacement with autologous fascia lata: a sociomedical study

In a series of 50 patients who underwent aortic valve replacement with frame-supported fascia lata, 32 were seen for a combined medical and psychosocial examination 10 to 33 months postoperatively. The investigation included a psychometric test battery and an interview concerning the patient's social and psychological situation at the time of the operation and at follow-up. Twenty-seven patients had improved in their New York Heart Association Functional Classification at the time of follow-up. In most instances NYHA classification correlated well with the patients' subjective opinion on their recovery. Those who for various reasons were not able to return to work did not consider themselves recovered. The employment rate after operation was 66%. There is a great need for more information and support to families as well as for more intensive rehabilitation efforts, especially vocational, for the postoperative patient.     

Evaluation of electrochemical properties of antibacterial ZnO layers deposited to 316LVM steel using atomic layer deposition

The presence of a biofilm can lead to the disappearance of the surrounding bone tissue and, as a result, disturb the osseointegration process. Unfortunately, both in the case of instability of the implant and long-term bacterial infections, there is often a need for reoperation as well as replacement of the implant, which in turn is associated with huge costs, but most of all discomfort for the patient associated with long-term hospitalization. In order to limit this unfavorable process, the physicochemical properties of the surface layer of implants are indicated. Therefore, the paper proposes applying a layer with antibacterial effect on the surface of 316LVM steel used in bone surgery. As part of the work, the ZnO layer was applied using the atomic layer deposition method with different parameters of the application process (different number of cycles at constant temperature). In the first stage, pitting corrosion resistance tests were carried out using the potentiodynamic method and studies using electrochemical impedance spectroscopy. The surface morphology tests using a scanning electron microscope were also complemented. Obtained results may form the basis for the development of more detailed criteria for the assessment of the final quality of medical devices used in the skeletal system.     

Computer understanding of document structure

We describe a system which is capable of learning the presentation of document logical structure, exemplary as shown for business letters. Presenting a set of instances to the system, it clusters them into structural concepts and induces a concept hierarchy. This concept hierarchy is taken as a reference for classifying future input. The article introduces the sequence of learning steps and describes how the resulting concept hierarchy is applied to logical labeling, and reports the results. © 1996 John Wiley & Sons, Inc.     

Electrophoretic Deposition,Microstructure, and Corrosion Resistance of Porous Sol–Gel Glass/Polyetheretherketone Coatings on the Ti-13Nb-13Zr Alloy

Metallurgical and Materials Transactions A - In this study, microporous composite sol–gel glass/polyetheretherketone (SGG/PEEK) coatings were produced on the Ti-13Nb-13Zr titanium alloy by...     

Phase-decomposition-related short-range ordering in an Fe–Cr alloy

A redistribution of Cr atoms related to a phase decomposition (PD) caused by an isothermal annealing at 415 °C in a 15.15 at.% Cr Fe–Cr alloy was studied in an ex situ way by the conversion electrons Mössbauer spectroscopy. Analysis of the spectra in terms of a two-shell model enabled the determination of probabilities of 17 different atomic configurations and average numbers of Cr atoms within the first (1NN) and the second (2NN) neighbor shells vs. annealing time, separately. The annealing-time evolution of these numbers, expressed in terms of the Cowley–Warren short-range order (SRO) parameters, was shown to follow the Johnson–Mehl–Avrami–Kolgomorov equation. The SRO parameter averaged over the 1NN–2NN shells was revealed to be linearly correlated with the average hyperfine field. Signatures in favor of the nucleation and growth mechanisms responsible for PD are also discussed.