X-ray diffraction and resistivity studies of titanium-molybdenum alloys

The phase transformation behavior of the metastable beta phase in hydrogen charged Ti-Mo alloys was investigated using electrical resistivity and X-ray diffraction techniques. Hydrogen charging was found to have little effect on athermal omega phase formation in a highly susceptible alloy (16 wt pct Mo) but suppressed athermal omega in alloys with compositions near the critical composition for the transition to diffuse (incommensurate) type omega (∼20 wt pct Mo). No evidence was found for a hydrogen induced omega phase in a concentrated alloy (30 wt pct Mo). The incipient stages of the beta + beta’ phase separation in Ti-30 wt pct Mo were detected after aging slightly below the beta transus.     

Boronizing of titanium-molybdenum alloys

Conclusions A study was made of the kinetics of the reaction of Ti-Mo alloys with boron. It is shown that the intensity of the reaction depends on the composition of the alloys. The rate of the reaction, which is a minimum at Mo contents of 10 and 20 at.%, is determined by the diffusion of atoms of the reacting components. Titanium alloys containing 10 or 20 at.% Mo may prove to be suitable for operation at high temperatures in boron-containing media.Translated from Poroshkovaya Metallurgiya, No. 12(180), pp. 66–69, December, 1977.     

X-ray diffraction line analysis of splat-cooled Al-rich Al-Cu alloys

Measurements of the line broadening and the line position were made for splat-cooled aluminium-rich aluminium-copper alloys. The line-broadening was studied by the modified Warren-Averbach method. The stability and the initial progress of decomposition during annealing are discussed. It was found that the X-ray line profile analysis is very useful for examination of the initial progress of decomposition in splat-cooled Al-Cu foils.     

X-ray diffraction study of alloys in the system Mo-Re-C

Summary An x-ray diffraction study of alloys in the system Mo-Re-C has led to the discovery of two ternary compounds. The compound Mo₃Re₂C has a structure of the -Mn type (a=6.86±0.01 A). The compound (Mo, Re)C has a structure of the NaCl type and contains a variable amount of rhenium, ranging between a few and 40 at.%. There exists a continuous series of solid solutions between Mo₂C and Re. The data obtained indicate a close relationship between the systems Mo-Re-C and W-Re-C.     

X-ray diffraction study of one-dimensionally disordered structure formation in Co-based alloys

Formation of one-dimensionally disordered (ODD) structures with non-random distribution of growth stacking faults (SF's) in Co-based alloys has been investigated by X-ray diffraction. It has been found that the usual process of growth of coarse crystals with fairly perfect h.c.p. lattice in pure Co is substituted for the accumulation of numerous thin non-randomly distributed lamellae with a h.c.p. structure in doped Co. This results in the growth SF's formation as isolated cubic type planes, clamped by neighbouring lamellae. The character of the SF's distribution in the final ODD structure is determined by ordering of the lamellae in the initial stages of the transformation.     

X-ray studies of cold-worked ternary alloys containing Pd-Ag-Au

The structure of highly deformed filings of the Pd-Ag-Au ternary alloy system has been studied by using the Warren-Averbach X-ray diffraction line profile analysis. The effective particle size and root mean square strain were determined over a range of compositions and were found to be anisotropic. Stacking fault probabilities were obtained from shifts in the peak positions. An extrapolation technique was employed for the determination of the twin fault probabilities which eliminates most of the ambiguity associated with the separation of the overlapping tails between the (111)-(200) peaks. Although a large range in composition was examined, very little variation was observed in the effective particle size, nonuniform microstrain, stacking fault probability, and twin fault probability. Consequently, these quantities are nearly constant except at the corners of the ternary diagram, where the pure elements are approached. Cold working had an appreciable effect on the lattice parameter at certain compositions. For alloys containing all three components both an increase and a decrease in the lattice parameter was observed as the palladium composition was varied. Deformed alloys containing palladium and silver gave lattice parameters which are essentially the same as those reported for the annealed state.     

X-ray diffraction study of decomposition in aluminum-silver alloys quenched from the melt

The age hardening of aluminum-4.5 at. pct (16 wt pct) silver alloys quenched from the melt indicates that the decomposition processes in rapidly cooled specimens differ from those in conventionally quenched ones. Therefore, decomposition products in specimens quenched from the melt by the two-piston and the mill techniques were investigated by means of X-ray diffraction at small and large angles. Several types of camera had to be applied to observe the various phenomena in the diffraction patterns. Guinier-Preston zones were present in the as-quenched state and were about twice as small as those in the specimens quenched from the equilibrium solid solution state. Instead of the well known precipitation sequence G.P. zones → γ′ → γ in specimens quenched from the solid state, the equilibrium phase γ was present before the first traces of the metastable γ′ phase appeared. The γ′ precipitates nucleated, grew, and disappeared more readily in the liquid-quenched than in the solid-state-quenched specimens causing an overlap of cold and warm hardening stages and an earlier attainment of the maximum hardness with aging. Part of this work was reported at the First European Conference on the Physics of Condensed Matter held in Florence in September 1971.     

Studies of lattice imperfections in deformed aluminum-based lithium alloys by X-ray diffraction

X-ray diffraction (XRD) intensity data from five different alloys of aluminum-zirconium-lithium and aluminum-magnesium-lithium, having extensive application in aircraft industries, were measured with a PHILIPS PW 1730 X-ray diffractometer. The microstructural parameters like coherent domain size, microstrain within the domain, and stacking faults were evaluated in the deformed lattice of the alloys by applying Fourier line-shape analysis. It has been observed in the deformed lattice that deformation faults, both intrinsic and extrinsic, are absent, whereas the twin fault has significant presence in the lattice and shows systematic changes with the increase of lithium content.     

X-ray and neutron diffraction anomalies preceding martensitic phase transformation in AuCuZn2 alloys

The present paper gives the results obtained by the X-ray and neutron diffraction studies on the single crystals of the beta-1 AuCuZn₂ alloys. As precursor phenomena, the dispersion relation of the [110] TA₁ phonon exhibits significant dip near 2/3 [110]q _max position and anomalous peaks appear around 1/3 and 2/3 [110]q _max positions. Characteristics of the interplanar force constants, obtained by the analysis of the dispersion relation, and the positions of the anomalous peaks predict the martensite structures to be formed in the beta phase alloys. In the present case, both the 6R and 18R martensites will be formed by cooling and/or under the stress field. This paper is based on a presentation made in the symposium “Pretransformation Behavior Related to Displacive Transformations in Alloys” presented at the 1986 annual AIMS meeting in New Orleans, March 2–6, 1986, under the auspices of the ASM-MSD Structures Committee.     

X-ray diffraction investigation of diffusion during the sintering of nickel-chromium and iron-chromium powder alloys

Summary The sintering of powder nickel-chromium and iron-chromium alloys was investigated by the x-ray diffraction technique. It was established that the rate of diffusion processes increases with rise in the nickel content of the nickel-chromium alloys, and in the iron content of the iron-chromium alloys, subjected to heat treatment under similar conditions.Translated from Poroshkovaya Metallurgiya, No. 8(56), pp. 22–27, August, 1967.The authors wish to express their gratitude to S. M. Solonin for helpful advice and L. O. Zhenni-Maiskaya for assistance in the investigation.     

Electrical resistivity of V-H alloys

The electrical resistivity has been determined at temperatures between 120° and 500°K for V-H alloys with hydrogen concentrations from 0 to 42.1 at. pct. A plot of the hydrogen solubility limit in vanadium shows that it increases from 0.5 at. pct at 227°K to 26.4 at. pct at 436°K. X-ray diffraction powder patterns indicated that alloys containing between 33.8 and 42.1 at. pct H were single-phase, bet, β-V hydride at room temperature. The resistivity of the 33.8 at. pct alloy closely approximated that of hydrogen-free vanadium, but the room temperature resistivity increased with increasing hydrogen concentration at the rate of 1.7 microhm-cm per at. pet H. These β alloys underwent one transformation at temperatures below 224°K and two more transformations near 450°K. The rationale has been based on increasing disorder of hydrogen in the interstices of the lattice with increasing temperature.     

An X-ray diffraction line profile of cold-worked hexagonal alloys Zn-Ag: η and ε phase

A detailed analysis of X-ray line broadening in filings of hexagonal zinc-silver alloys containing 0.9, 1.9 at. pct (η-phase) and 13.1, 16.8, 20.6, 24.6, and 28.8 at. pct Ag (ε-phase) have been made using Warren and Averbach’s method of Fourier analysis. The diffraction profiles from fault-unaffected [H-K = 3N] reflections 10.0, 00.2, 11.0, 20.0, 11.2, 00.4 and fault-affected [H-K = 3N ± 1] reflections 10.1, 10.2, 10.3, 20.1, 20.2, 20.3 have been chart recorded in a Geiger counter X-ray diffractometer equipped with a LiF crystal monochromator. With an awareness of the small anisotropy in average domain size and strain, the deformation stacking fault probabilityα and growth fault probabilityβ have been calculated from a least-squares analysis performed on H-K = 3N ± 1 reflections. It has been observed that values ofα are significantly small while values ofβ are negligible — an observation remarkably different from hexagonal alloys studied earlier. The dislocation densityρ and the stacking fault energyγ have been evaluated for all the alloy compositions. Since the primary slip plane may be either basal or prismatic in hcp structures, a favorable slip mode in this system has been discussed on the basis of stacking fault energy and unit cell parameters.