Specific analysis of EBSD data to study the texture inheritance due to the β → α phase transformation

A specific processing of EBSD data is proposed to study the texture inheritance of titanium or zirconium alloys. A non standard misorientation map is calculated to localise the colonies inherited from the same parent grain. The calculation of the parent orientation from its inherited variants detailed in previous works has been adapted to the data obtained from an automated EBSD analysis. Finally, a method to derive the orientation map of the parent phase from that of the inherited phase is proposed. The resulting and COMs are used to study some aspects of the variant selection occurring in the transformation of a T40 sample.     

Similarity solutions in axisymmetric mixed-convection boundary-layer flow

The similarity equations for mixed-convection axisymmetric boundary-layer flow are considered. The equations involve a buoyancy parameter and a curvature parameter . The equations are solved numerically and it is found that for large , and of O(1), an asymptotic solution is approached, the nature of which is discussed. When is also large, of O(^1/4), the problem, at leading order, becomes independent of the mainstream and the free-convection limit is obtained. This problem is also discussed, including the behaviour for large values of ₀, the free-convection curvature parameter. For < 0 we find that the solution can be continued past the point where the wall heat transfer becomes zero (where previous mixed-convection similarity solutions in plane geometry were terminated) with the solution ending as 0^–. The nature of this limit is also discussed. For < 0 it is also found that there are solutions only in _b = < 0 with two branches of solution bifurcating out of = _b , and values of _b are computed for a range of . The behaviour of the solution for large values of the curvature parameter , and of O(1), is discussed where it is shown that the solution proceeds in inverse powers of log .     

Preferentially orientated precipitation in MnTiO3 single crystals

Preferentially orientated precipitation of -TiO₂ (rutile) needles in single crystals of MnTiO₃ grown by a floating-zone method under a controlled atmosphere of oxygen fugacity was studied. Optical microscopy and X-ray analysis revealed that the orientation relation between the -TiO₂ precipitates and the MnTiO₂ matrix is: {000 1}MnTiO₃// {111}-TiO₂ and 11¯20MnTiO₃// 110-TiO₂. The precipitation phenomenon was explained by introducing a nucleation and growth mechanism which was experimentally supported by heat treating experiments.     

Investigations of the copper isotope effect in oxygen-deficient YBa2Cu3O7−δ

We present data on the copper isotope effect (⁶³Cu-⁶⁵Cu), C_u =-nT_c/nm_Cu, for two isotopic pairs of oxygen-deficient YBa₂Cu₃O_7–, where varies between 0.06 and 0.52. _Cu is below 0.01 at =0.06 (fully oxygenated), it takes values between –0.14 and –0.34 in the 60 K plateau. Larger negative values of _Cu are observed away from the plateau. The dependence of _Cu is similar to that of the pressure effect dnT_c/dP.     

Mössbauer study on the magnetic state of iron particles in Fe-N and Fe-Zr-N soft magnetic thin films

The magnetic state of -Fe particles and the behaviour of nitrogen and zirconium during annealing in Fe₉₆N₄ and Fe_85.6Zr_7.6N_6.8 magnetic thin films have been studied by conversion electron Mössbauer spectroscopy for ⁵⁷Fe. The crystalline phases present in the Fe-N annealed films were -Fe and -Fe₄N, and those in the Fe-Zr-N annealed films were -Fe and ZrN. In the Fe-N films annealed below 300°C, about 60% nitrogen is incorporated interstitially into -Fe and the rest is used for the formation of -Fe₄N. In the Fe-N film annealed at 500°C, almost all nitrogen participates in the formation of -Fe₄N, leading to the grain growth of -Fe particles and an increase in coercive force. The values (291–325 kOe) of internal magnetic field of iron sites in -Fe in the Fe-Zr-N films are much smaller than that (333 kOe) of the iron site in pure -Fe. Even if the Fe-Zr-N films were annealed at 500–700°C, some zirconium and nitrogen is still incorporated substitutionally and interstitially into -Fe, respectively. In particular, the substitutional zirconium depresses the grain growth of -Fe particles, perhaps due to a chemical interaction between zirconium and iron.     

Vibrational properties of wood along the grain

The dynamic Young's modulus (E_L) and loss tangent (tan _L ) along the grain, dynamic shear modulus (G_L) and loss tangent (tan _S) in the vertical section, and density () of a hundred spruce wood specimens used for the soundboards of musical instruments were determined. The relative acoustic conversion efficiency ( ) and a ratio reflecting the anisotropy of wood (, (E_L/G_L)(tan _S/tan _L)) were defined in order to evaluate the acoustic quality of wood along the grain. There was a positive correlation between and , and the variation in was larger than that in . It seemed logical to evaluate the acoustic quality of spruce wood by a measure of . By using a cell wall model, those acoustic factors were expressed with the physical properties of the cell wall constituents. This model predicted that the essential requirement for an excellent soundboard is smaller fibril angle of the cell wall, which yields higher and higher . On the other hand, the effects of chemical treatments on the and of wood were clarified experimentally and analyzed theoretically. It was suggested that the and of wood cannot be improved at the same time by chemical treatment.     

Direct and inverse heat-conduction problems for a semiinfinite rod for a partial outflow of heat through the surface

Analytical solutions of the direct and inverse problems of nonstationary heat conduction in a thin semiinfinite rod are given for the case of radiative heat fluxes at the lateral surfaces and a partial outflow of heat by convection and radiation through the end of the rod.Notation thermal diffusivity - x₁ coordinate along the length of the rod - t₁ time - t=t₁/d² dimensionless time (Fourier number) - x=X₁/d relative coordinate - T_o initial temperature - Boltzmann constant - Sk=aT_c ³d/ Stark number - Bi=d/ reduced Biot number - emissivity Translated from Inzhenero-Fizicheskii Zhurnal, Vol. 47, No. 1, pp. 148–153, July, 1984.     

Microstructure-property studies in friction-stir welded, Thixomolded magnesium alloy AM60

Thixomolded magnesium alloy AM60 plates joined by friction-stir welding were observed to be as strong or stronger than the unwelded base material. The thixotropic microstructures of the as-molded plates consisted of either 3% or 18% primary solid fraction of -Mg globules (45 m average size) in a eutectic mixture consisting of -Mg grains (10 m) surrounded by Mg₁₇Al₁₂ intermetallic grains in the -Mg grain boundaries (having an average size of 1–2 m). This complex, composite microstructure became a homogeneous (Mg + 6% Al)), recrystallized, equiaxed grain (10–15 m) microstructure in the weld zone.     

The athermal α → ω transformation in Zr-2 at% Nb alloy

The athermal transformation in Zr-2 at.% Nb alloy has been investigated by transmission electron microscopy. Analysis of the selected-area diffraction pattern has shown that the orientation relationships between the omega and the parent-phase in quenched Zr-2 at.% Nb alloy are the same as have been previously observed for the reaction in pure zirconium. Thus it was deduced that the direct transition has taken place in the alloy during cooling. The-originated -particles were visualized using the dark-field technique. The formation of the athermal omega in the-region of-stabilized Zr-Nb alloy is discussed in terms of the relative positions of the free energy equilibrium curvesT ₀ ,T ₀ ,T ₀ and the correspondingM _s ,M _s andT _s start curves. It is concluded that the omega phase can occur over a much wider range of alloy compositions than is usually recognized on the basis of transformation data.     

Structure and properties of injection-moulded nylon-6

The microstructure and morphology of injection-moulded nylon-6 has been studied using wide-angle and small-angle X-ray diffraction, optical microscopy and a density measurement technique. A non-spherulitic surface layer consisting of a metastable pseudohexagonal phase surrounds the moulding and the thickness of the layer is sensitive to mould temperature. This outer structure gives way to a monoclinic phase containing spherulites between 3 and 6 m diameter. The central core of the moulding consists almost entirely of the phase with spherulites 6 m diameter, approximately. Exposure of nylon-6 to boiling water had no significant effect on the morphology of the moulding but the phase in the surface layer was transformed to the monoclinic phase.     

Experimental evaluation of relative mode parameters in the irregular earth-to-ionosphere waveguide

Conclusions A model for representing the propagation of superlong waves was selected. Certain relative mode parameters ()₁, ()₂, ()₃, (V)₁, (V)₂, (V)₃, C₁, C₂, and C₃ can be used in order to account for the time-measurement error produced as a resuit of the double-mode signal propagation, to determine in a semiempirical manner the ionosphere's effective reflection height at night and in the daytime, to calculate and apply signal-propagation corrections which take into account phase velocity changes due to variations in the ionosphere height from day to day, and to calculate the fields of transition paths.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 75–78, August, 1974.     

Heat transfer in plane film formation

A mathematical model is obtained for the process of cooling with formation of a planar film. The solution obtained is verified experimentally.Notation mean axial velocity gradient - v_x current axial velocity - v_o initial polymer velocity - v₁ sampling velocity - K draw ratio - deformation rate tensor - x, y, z spatial coordinates - X, Y dimensionless coordinates - L() differential operator - T temperature - T_o initial temperature - T_c temperature of surrounding medium - dimensionless temperature - dimensionless temperature averaged over film thickness - thermal-diffusivity coefficient - 2_o initial film thickness - thermal conductivity - heat-transfer coefficient - f(X) distance function - Bi Biot criterion, Bi_o, Biot criterion calculated for initial film thickness - Gz* modified Graetz criterion - V dimensionless velocity - ₁, ₂, ₃ heat-transfer coefficients produced by radiation, free convection, and forced convection - v_c, _c mean velocity and film half-thickness in formation zone - T₁ calculated temperature value - T₂ experimental temperature value - l formation zone length Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 5, pp. 854–858, November, 1979.     

The morphology of α′ martensite in a two-phase (α+γ) Fe-Cr-Ni stainless steel

Both lath-shaped and martensites are induced by tensile deformation within of a two-phase ( + ) Fe-Cr-Ni stainless steel, forms from the through the at an intersection of two crystals. These are observed both when is surrounded by and when borders . The amount of strain at which both and nucleate, increases with test temperatures in the range –196 to 50° C. Adjacent laths are either twin-related, or 5, 9, 15 or 19° off the twin relationship, as found by analysing electron diffraction patterns.     

Ageing characteristics of cast Zn-Al based alloy (ZnAl7Cu3)

Microstructure and ageing characteristics of a cast Zn-Al based alloy (ZnAl7Cu3) were studied using X-ray diffraction, electron scanning microscopy and back-scattered diffraction techniques. Two stages of phase transformation, i.e., decomposition of zinc rich phase and four phase transformation, + T + , were detected during ageing at 150°C. Electron back-scattered diffraction technique was applied in distinguishing both zinc rich and phases.     

Martensitic transformations in Ti-Mo alloys

A detailed investigation has been made of the structure of alloys of the Ti-Mo system containing up to 10wt% Mo, water-quenched from the-phase region. With increase in molybdenum content, the martensite structure changes from hexagonal () to orthorhombic () at 4 wt% Mo, and at 10 wt% Mo, the structure is completely retained . For alloy compositions <4 wt% Mo, there is a diffusional component in the transformation of the -phase at the quench rates employed. There is a transition, with increase in molybdenum content, in morphology (from massive to acicular) and in substructure (from dislocations to twins). However, the transitions in crystallography, morphology and sub-structure are not directly related to one another except for an abrupt loss of dislocation substructure at the/ transition. The to crystallographic transition has the characteristics of a second order transformation, and evidence has been obtained of the existence of a spinodal within the metastable orthorhombic system. The orthorhombic martensites of Ti-6 and 8 wt% Mo decompose during quenching producing a fine modulated structure within the martensite plates, consistent with a proposed spinodal mode of decomposition.     

Eutectoid decomposition in Fe2Si5 based alloys with a small amount of 10(Pd, Pt) and 11(Cu, Ag, Au) group elements

The addition of a small amount of Cu is effective in accelerating the + Si eutectoid decomposition. Some elements (Pd, Pt, Ag and Au) that are expected to have similar chemical properties were added to an Fe₂Si₅ based alloys up to 1.0 at.% to examine whether a similar effect could be revealed. The microstructures, X-ray diffraction and differential thermal analysis (DTA) of slowly solidified or heat treated specimens were investigated in detail. The solubility of all containing elements into the phase was less than 0.2 at.% for the slowly solidified specimen. The excess of the additive solidified as a phase of a eutectic with the Si phase. On the other hand, the solubility of these additives in the phase was classified into two groups. The first group had higher solubility in the phase than that in the phase. The solubility of the other group was as low as that in the phase. Pd and Au belonged to the former and Pt and Ag belonged to the later. The acceleration of the eutectoid decomposition was only observed in the former group but it was negligible in the later group. The existence of the eutectic melt at the annealing temperature was effective on the coarsening of the eutectoid structure but not essential for the acceleration. The eutectoid decomposition strongly depended on the solubility of these elements into the phase.     

Oriented mosaic model analysis of anisotropic thermoelectric properties of heterogeneous materials

Thermoelectric properties of heterogeneous materials are discussed in terms of a randomly oriented rectangular plate-like mosaic of anisotropic crystalline grains embedded in a homogeneous host material. Anisotropies in effective thermoelectric parameters and the values of thermoelectric parameters can be related to the mean orientation of the plate-like grains which, in turn, can be related to the orientation factor of Lotgering. They are also functions of various parameters such as dimension ratios , and of electrical resistivities, thermal conductivities, and the Seebeck coefficient, respectively, of grains to those of host medium. Use of f-dependent anisotropies in conjunction with relative magnitudes of electrical and thermal conductivities as well as of the Seebeck coefficient, allows , and to be estimated, which characterize the intergranular medium.     

Thermal Expansion and Isothermal Compressibility of TlIn1 – xNdxSe2 (0 ≤ x≤ 0.08) Crystals

The thermal expansion coefficient () and isothermal compressibility ( _T ) of TlIn_{1 – x} Nd _x Se₂(0 x 0.08) crystals were measured between 77 and 400 K. In the range 77–160 K, both and _T increase with temperature, the increase in being much steeper. At higher temperatures, and _T change very little. The observed composition dependences of and _T are interpreted in terms of energy-band structure.     

The mechanism of continuous dissolution of the lamellar structure in aged Al 22 at% Zn alloy

The mechanism of continuous dissolution was studied using transmission electron microscopy, X-ray diffraction and hardness measurements. The metastable phase was identified in the first stage of dissolution nucleating at the - boundaries. Interface dislocations at the - boundaries forming a perpendicular net in the 110 directions were identified as of screw character and of Burgers vector b=1/2a 110. During dissolution a change of shape of precipitates occurs leading to their fragmentation and to a change of the direction of boundaries into 110 directions.