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Year 2007 No 1

Dobrovská J., Stránský K., Dobrovská V.
SEGREGATION BEHAVIOUR AND CHEMICAL HETEROGENEITY OF AS-CAST AND HEAT TREATED NICKEL-BASED SUPERALLOY IN 738LC
Keywords: Nickel alloys|Solidification|Segregation|Partition coefficient|Fourier number|
No 1 (2007), p. 7-16
  mag01.pdf (483 kB)
mag01_eng.txt (3 kB)  

Longauerová M., Fedorová M., Longauer S., Kadlec J., Bořuta J., Fujda M., Janák G., Vojtko M.
HETEROGENEITIES OF CHEMICAL COMPOSITON IN CAST PRODUCTS
Keywords: Slabs|surface segregation|structure heterogeneities|centreline noncompactibilities|round blooms|central segregation|
No 1 (2007), p. 17-25
  mag02.pdf (293 kB)
mag02_eng.txt (3 kB)  

Takahashi M., Ikeuchi K.
ELECTROSTATICALLY INDUCED PRECIPITATION OF SILVER IN SILVER-IMPREGNATED GLASS ANODICALLY-BONDED TO SILICON
Keywords: anodic bonding|silicon|glass|silver|ion substitution|prevention of joint defect|
No 1 (2007), p. 26-35
  mag03.pdf (2 MB)
mag03_eng.txt (1 kB)  

Bujnošková K., Drápala J.
STUDY OF SEGREGATION CHARACTERISTICS OF TANTALUM IN SINGLE CRYSTALS OF LOW-ALLOYED TUNGSTEN AND MOLYBDENUM ALLOYS
Abstract
During crystallization processes a redistribution of admixtures and impurities in the solid and liquid phases happens on the phase interface in the solidification interval due to their different solubility. A basic parameter characterizing the distribution of admixtures and impurities between the solid and liquid phases is the segregation coefficient. Its knowledge is important for selecting of a convenient crystallization method of refining, preparation of quality single crystals and study of segregation micro- and macro-inhomogeneities. The growth of single crystals from melts may be accompanied by creating a sequence of structural imperfections in the solid phase which is given by the conditions of crystallization and the crystal chemical composition. A periodical variation of the crystallization rate happens under certain conditions of the heat and mass transfer, which leads to a variation of the character of distribution of admixtures in the volume of the growing single crystal and its substructure. An accumulation of admixtures in front of the crystallization front and increasing of the crystallization undercooling may cause a considerable rise of the speed of movement of the crystallization front and changes of the admixture occupation in the growing crystal on the phase boundary surface. The variation of the microscopic crystallization rate causes a creation of a band structure observed on longitudinal sections of single crystals.
The aim of our experimental work was to study an influence of crystallization conditions on the segregation and structural characteristics of single crystals of low-alloyed molybdenum and tungsten alloys. Low-alloyed single crystals of W and Mo doped with Ta were prepared by the electron beam floating zone melting (EBFZM) applying three different zone pass rates - 3, 5 a 1 mm/min. The electron wave dispersive analysis was used for the determination of admixtures concentration on longitudinal sections. On the basis of chemical analysis were found the growth bands in these single crystals that are characterized by the sinusoidal wave of concentration profiles. Further the concentration relations in crystal and freeze zone in order to ascertain of effective segregation coefficients of alloying elements were determined. In order to evaluate relations between chemical inhomogeneity and structural defects and their influence on properties of single crystals there were experimentally investigated.

Keywords: segregation|tungsten|molybdenum|tantalum|zone melting|segregation coefficient|
No 1 (2007), p. 36-43
  mag04.pdf (208 kB)
mag04_eng.txt (2 kB)  

Greger M., Kocich R., Kuřetová B., Kander L.
MICROSTRUCTURAL EVOLUTION OF MAGNESIUM ALLOYS
Keywords: magnesium alloys|deformation|rolling|torsion test|
No 1 (2007), p. 44-51
  mag05.pdf (674 kB)
mag05_eng.txt (2 kB)  

Dománková M., Marek P., Moravčík R.
EFFECT OF ANNEALING AT 650°C ON PRECIPITATION IN CHOSEN AUSTENITIC STAINLESS STEELS
Keywords: austenitic stainless steels|sensitisation|precipitation|secondary phases|intergranular corrosion|
No 1 (2007), p. 52-60
  mag06.pdf (897 kB)
mag06_eng.txt (3 kB)  

Marek P., Dománková M.
INFLUENCE OF 40 % DEFORMATION ON SENSITISATION CHARAKTERISTIC OF 316 AND 316 L AUSTENITIC STAINLESS STEELS
Keywords: austenitic stainless steels|deformation|sensitisation|precipitation|
No 1 (2007), p. 61-67
  mag07.pdf (1 MB)
mag07_eng.txt (3 kB)  

Hajduga M., Jędrzejczyk D.
THE EFFECT OF OXIDE PRECIPITATION ON THE QUALITY OF STEEL ELEMENTS SHAPED BY GAS CUTTING
Keywords: high temperature oxidation|gas cutting|oxide precipitations|
No 1 (2007), p. 68-75
  mag08.pdf (633 kB)
mag08_eng.txt (3 kB)  

Drápala J., Morávková Z., Vrbický J., Dostál V., Sidorov E.V.
THE THEORETICAL ASPECTS OF CRYSTALLIZATION IN TERNARY ALLOYS AND THE CHARACTER OF SEGREGATION PROCESSES AT EQUILIBRIUM AND NON-EQUILIBRIUM SOLIDIFICAT
Keywords: ternary system|crystallization|liquidus|solidus|segregation coefficient|
No 1 (2007), p. 76-84
  mag09.pdf (256 kB)
mag09_eng.txt (2 kB)  

Isayev O., Nosochenko O., Kislitsa V.
DEVELOPMENT THE CONTINUOUS CASTING TECHNOLOGY OF Nb-CONTENT STEEL GRADES FOR INTERNAL SLABS AND PLATES QUALITY IMPROVEMENT
Keywords: line pipe grades of steel|Nb-content|tundish|inclusions|residual time|refining|
No 1 (2007), p. 85-93
  mag10.pdf (347 kB)
mag10_eng.txt (3 kB)  

Purmenský J., Foldyna V.
DEVELOPMENT OF LOW ALLOY AND MODIFIED CHROMIUM STEELS STRENGTHENED BY NANOPARTICLES
Keywords: Creep resisting steels|structural stability|nanoparticles|
No 1 (2007), p. 94-100
  mag11.pdf (480 kB)
mag11_eng.txt (3 kB)  

Hernas A., Herian J., Wylaź P.
MICROSTRUCTURE AND PROPERTIES OF HOT ROLLED 42CrMo4 STEEL CHARGE AND RINGS
Keywords: Steel rings|heterogeneity|microstructure|hardness|modification of process technology|
No 1 (2007), p. 101-108
  mag12.pdf (2 MB)
mag12_eng.txt (2 kB)  

Pascu D.-R., Pascu M.
STRUCTURAL HARDENING OF THE G20Mn6 CAST STEEL WITHIN THE CONSTRUCTION OF THE WELDED SAFETY LOCKS FROM THE RAILWAY CONTAINERS
Keywords: safety lock|G20Mn6 steel|hardening|structural examination|mechanical testing|heat treatment|
No 1 (2007), p. 109-116
  mag13.pdf (1 MB)
mag13_eng.txt (3 kB)  

Lejček P., Janovec J., Konečná R.
NANOSEGREGATION PHENOMENA AT GRAIN BOUNDARIES OF METALLIC MATERIALS
Keywords: segregation|grain boundaries|prediction|thermodynamics|ferrite alloys|
No 1 (2007), p. 117-130
  mag14.pdf (1 MB)
mag14_eng.txt (3 kB)