The effect of microstructure and composition on the properties of vapour quenched AlCr alloys—II. Tensile properties

The effect of chromium and iron additions and of annealing and working on the microstructure and tensile properties of vapour quenched AlCr and AlCrFe alloys has been determined. Tensile strengths of the worked AlCrFe alloys were in the range 568–831 MPa. Chromium in solid solution or iron present as iron-rich precipitates increased the yield stress by 44.7 MPa/at.%Cr and 333 MPa/at.%Fe respectively. The contributions to the yield strength of AlCr alloys were solid solution 40% and dislocation density/cell size 60% and to the yield strength of AlCrFe alloys were solid solution 25%, iron-rich precipitates 42% and dislocation density/cell size 33%. Vapour quenching may allow the more efficient use of alloying elements in the strengthening of Al-alloys and greater flexibility in obtaining the desired combination of solute concentration, particle volume fraction and particle size.     

The effect of microstructure and composition on the properties of vapour quenched AlCr alloys—I. Young's modulus

AlCr and AlCrFe alloys were quenched from the vapour phase onto substrates held at 230–370°C. Up to 5.6at.%Cr (10.7 wt%) was retained in solid solution. The effect of chromium content (C_Cr) on Young's modulus (E) was measured; E increased at a rate of 5.7 GPa/at.%Cr. The addition of iron up to 0.5at.% (1.0 wt%) had no detectable effect on Young's modulus of the AlCr binary alloy. Conversion of chromium in solid solution to intermetallic particles did not affect the modulus. The specific modulus (E/ρ where ρ = density) increased with chromium content and E/ρC_Cr, was 1.35 MNm/kg at.%Cr. Vapour quenched AlCr alloys have greater potential for improving the modulus of Al-alloys compared with AlLi or Al powder alloys containing iron, manganese or chromium.     

Influence of crystallization conditions on the structure and modifying ability of Al–Sc alloys

The influence of the modes of thermal-and-temporal treatment and cooling rate of metallic alloys on crystallization regularities of Al–Sc alloys and their structure, properties, and modifying ability are established. Castings of Al–Sc alloy, which were prepared by the electrolysis of salt melts KF–NaF–AlF₃–Sc₂O₃ at 820–850°C, are used as the initial charge for casting. It is established that, by varying the magnitude of melt overheating and casting temperature, it is possible to vary the crystal shape, amount, and size in wide limits. The modifying action of cast and rapidly quenched master alloys, as well as the master alloy produced by electrolysis, is tested for Al–4.5% Cu alloy. The largest effect of milling the structure of the Al–4.5% Cu–0.4% Sc alloy is attained when using the rapidly quenched master alloy.     

Effect of the sintering temperature and time on the structure and phase composition of temperature stable hard magnetic materials of the REM–Fe–Co–B system

The structure, the phase composition, and the distribution of alloying elements in the structure of temperature stable hard magnetic materials of the REM–Fe–Co–B system (REM = rare-earth metals), which are prepared under different manufacturing conditions, namely, at different sintering temperatures and times, have been studied. The phase composition, the local chemical composition of phases, the volume fraction of pores, and the manufacturing conditions that allow one to prepare the structure ensuring high magnetic properties have been determined.     

Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys

Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measurement. The samples were single phase with cubic MgCu2- type structure; with the increase of Dy content, Tc decreased from 240 K （TbCo2） to 130 K （DyCo2）, and the maximum magnetic entropy change ｜ △SM,max｜ increased from 3.133 to 8.176 J/kg-K under low magnetic field of 0-2 T. The Arrott plot and the change of ｜△SM,max｜ showed that magnetic phase transition from second order to first order occured with the increase of Dy content between x=-0.6 and 0.8.     

Excess aluminium effect on the composition and microstructure of Mo–Al alloys from aluminothermic reduction of MoO3

The effect of aluminium excess on the composition and microstructure of Mo–Al alloys from aluminothermic reduction of metallurgical-grade MoO₃ was investigated. Aluminium excess ranged from 0 to 30% (in wt-%) with respect to the stoichiometric amount. The results showed that molybdenum yield increases for higher excess aluminium. The microstructure and composition of the alloys were investigated using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD). The following phases were observed in the microstructures: Mo_ss, Mo₃Al, and Mo₃Al₈, besides particles of Al₂O₃. The results also showed that metallurgical-grade MoO₃ leads to a product containing significant amounts of silicon.     

The effect of hydrogen on the crystallization behavior of amorphous PdSi alloys

Differential scanning calorimetry, X-ray diffractometry and Optical metallography were used to study the effect of hydrogen atmosphere and surface treatment on the crystallization process in PdSi metallic glasses. In Pd₈₀Si₂₀ metallic glasses, the surface treatment by mechanical polishing with 1200 SiC induces surface crystallization in which preferred nucleation at the surface occurs, while homogenous crystallization occurs in as-quenched samples without surface grinding. In amorphous Pd₈₅Si₁₅, the crystallization occurs simultaneously from the sample surface and in the bulk. Surface treatment by mechanical polishing does not change the crystallization morphology. These results were not affected by the atmosphere of argon or hydrogen. It is shown that the surface crystallization, which is dominant in the initial stages of the transformation, is revealed by the low temperature shoulder of the main peak of crystallization in a DSC trace. The process of crystallization of amorphous Pd₈₀Si₂₀ and Pd₈₅Si₁₅ is found to be impeded by absorbed hydrogen, this having been measured by the increase of both crystallization temperature and activation energy for crystallization process in a hydrogen environment. Such crystallization behavior can be explained by assuming that hydrogen reduces the free volume available for rearrangements of host atoms of the metallic glasses.     

Effect of heat treatment on the crystalline structure of martensite in iron-, nickel-, manganese- and silicon-doped CoW and CoMo alloys

X-ray investigation of the crystalline structure of martensite of CoWFe, CoMo(Fe, Ni, Mn, Si) single crystals is performed after quenching and preliminary aging in α and β phases. Continuous decomposition of α and β solid solutions at aging at temperatures 500–700°C is observed. In Fe- and Ni-doped alloys the multilayer martensile polytypes are formed. In CoMoFe and CoMoNi single crystals such polytypes are found at the satellite stages of decomposition.     

Electronic and structural studies of grain boundary strength and fracture in L12 ordered alloys—III. On the effect of stoichiometry

In order to clarify the effect of alloy stoichiometry on the grain boundary strength and fracture behavior of L1₂-type A₃B compounds, the mechanical properties of Ni₃Al, Ni₃Ga, Co₃Ti and Ni₃(Al_0.52Mn_0.48) compounds were investigated at room temperature. Also, the effect of interstitial atoms of boron and hydrogen and the interaction of its effect with alloy stoichiometry were observed. The result indicated that the magnitude of compositional dependence of alloy stoichiometry on the elongation, the ultimate tensile strength and fracture behavior varied as Ni₃Al > Ni₃Ga > Co₃Ti > Ni₃(Al_0.52Mn_0.48). It was also revealed that the effect of interstitial atoms on the grain boundary cohesive strength is independent on and then additive to the effect of alloy stoichiometry. The significance of the grain boundary structure and related electronic environment in the grain boundary region was, in the geometrical frame, emphasized to interpret the present behavior.     

The effect of FeS film on the surface of iron powder particles on mechanical properties and fracture of Fe–Cu–C alloys

This article provides a new kind of P/M processing by designing thin-layered FeS film coated on the surface of iron powder particles for preparing high density Fe–Cu–C materials. Experimental results showed that FeS lubricating coating on the surface of iron powder particles was significant as a means of reducing friction in the pressing process of Fe–Cu–C alloys. After being pressed, the green density increased from 7.18 to 7.42?g?cm^?3. The sintered density increased from 7.10 to 7.37?g?cm^?3. In the sintering process, the FeS was liquid, and useful in purifying particle surface and strengthening grain boundaries to improve the mechanical properties. The hardness and tensile strength of the Fe–2.0Cu–0.9C–0.5FeS₂ material were 80.5 HRB and 590?MPa. Analysis of fracture showed the main fracture was transgranular fracture. And FeS spherical particles gathered in the pores of the Fe–Cu–C alloys.     

Calorimetric study and description of the composition dependence of the mixing enthalpy of liquid Cu—Fe—Co aloys

The partial enthalpy of cobalt in ternary liquid Cu-Fe-Co alloys is studied at a temperature of 1873 K along sections characterized by ratios x _Cu/x _Fe = 3, 1, and 1/3 in the composition range x _Co = 0–0.55. The experiments have been carried out on a high-temperature isoperibolic calorimeter. The composition dependences of the partial mixing enthalpy of the cobalt and the integral mixing enthalpy of Cu-Fe-Co melts are described using the Muggianu-Redlich-Kister equation over the entire concentration triangle. The contributions of a ternary interaction to the partial mixing enthalpy of cobalt and the integral mixing enthalpy of Cu-Fe-Co melts are calculated.     

Effect of the solidification and aging conditions on the mechanical properties of Pb–Ca–Sn battery alloys

The influence of the mold temperature on the mechanical properties and the structure of Pb–Ca–Sn battery alloys during their solidification and subsequent aging is studied.     

The relationship between clients’ conformity to masculine norms and their perceptions of helpful therapist actions.

T. J. G. Tracey et al.’s (2003) common factors model derived from therapists and psychotherapy researchers has provided a parsimonious structure to inform research and practice. Accordingly, the current authors used the 14 common factor categories identified in Tracey et al.’s model as a guide to code clients’ perceptions of helpful therapist actions (e.g., intervention, way of being) in short-term psychotherapy. Next, they conducted a cluster analysis to establish meaningful subgroups of clients based on clients’ perceptions of helpful therapist actions. Finally, they explored if clients in these subgroups differed in their report of conformity to masculine norms. Clients (N = 161) from a university counseling center were recruited for the current study. Results revealed 3 clusters of clients based on their perceptions of helpful therapist actions: Insight (44%), Relationship (30%), and Information (26%). In contrast, Tracey et al. found 3 clusters: Bond (which includes Insight and Relationship), Information, and Structure of therapy (not found in the current study). Clients in the Insight and Relationship clusters reported more conformity to masculine norms as compared with clients in the Information cluster. There were no sex differences across clusters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)