Amorphization of Ti1−x Mn x

Three amorphous Ti_1−x Mn _x alloy powders, withx = 0.4, 0.5, and 0.6, were prepared by mechanical alloying (MA) of the elemental powders in a high-energy ball mill. The amorphous powders were characterized by X-ray diffraction (XRD) and high-resolution transmission elec- tron microscopy (HRTEM). The crystallization temperatures for these alloys detected by dif- ferential scanning calorimetry (DSC) varied from 769 to 830 K. The calculated enthalpies of mixing in these amorphous phases are relatively small compared with those for other Ti-base binary alloys. The criteria for solid-state amorphization reaction are examined. It is suggested that the kinetics of nucleation and growth favors the formation of the amorphous phases and the supply of atoms for nucleation and growth is predominantly through the defective regions induced by MA. Formerly Graduate Student, National Tsing Hua University     

Phase structure of the Ti1Cu1− x Fe x system

The phase structures of Ti₁Cu_1?X Fe _X withX=0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 were investigated by means of Mössbauer spectroscopy, X-ray diffraction, and microprobe. The Mössbauer spectral and X-ray diffraction data imply that the γ-TiCu and CsCl structure phases coexisted in theX=0.1 andX=0.2 alloys. The Mössbauer spectrum ofX=0.1 is a sum of two components, one quadrupole doublet with larger quadrupole splitting and one with smaller quadrupole splitting. Mössbauer spectra for alloys other thanX=0.1 are simple doublet. By comparison, Ti₁Cu_0.5Fe_0.5 has smaller linewidth and higher isomer shift than Ti₁Co_0.5Fe_0.5. This might be attributed to stronger interaction between Cu and Fe than that between Co and Fe. The solid solubility of Fe in the γ-TiCu lattice is very limited to about 1 at. pct. On the contrary, CsCl structure phase is homogeneous in the range of Ti₁Cu_1?X Fe _X ,X=0.25 to maybeX=1. The lattice parameter of CsCl structurevs concentration of Cu is related linearly.     

Enthalpy of formation of B2-Fe1−x Al x and B2-(Ni,Fe)1−x Al x

The enthalpy of formation of the ordered B2 phases in the Fe-Al and Fe-Ni-Al systems was measured with very good accuracy using a special, laboratory-built differential-solution calorimeter. The measurements were performed at 1073 K as a function of composition, with an accuracy of about 1 pct. The enthalpy of formation of B2-FeAl is most negative for the composition Fe_0.50Al_0.50 (−36.29 kJ/mol). Compounds with Al contents less than about 40 at. pct show a deviation from the linear dependence of the enthalpy of formation with composition which prevails for Al contents larger than 40 at. pct. Upon replacing Fe by Ni while maintaining a constant Al content, the enthalpy of formation of B2-(Fe,Ni)Al compounds becomes more negative. With decreasing Al content and for a constant Fe/Ni ratio, the enthalpy of formation of the ternary phase becomes less negative.     

Microstructure and mechanical properties of sputter-deposited Cu1−x Ta x alloys

The microstructures and mechanical properties of a family of sputter-deposited Cu_1−x Ta _x (0<x<0.18) alloys have been investigated. The as-deposited microstructures for all film compositions consisted of a polycrystalline, face-centered-cubic (fcc) Cu matrix, with varying levels of Ta in solid solution, plus a very high density of discrete, 1 to 3 nm, fcc Ta particles. Decreased deposition temperature (−120 °C vs 100 °C) increased the level of Ta in solid solution. After annealing (900 °C for 1 hour) the as-deposited 6 at. pct Ta films, the Cu matrix grains remained submicron and the Ta particles remained fcc with no apparent particle coarsening. Additionally, the fcc Ta particles were found before and after annealing to be oriented identically with the Cu matrix and aligned on {111} and {100} habit planes. Annealing 17 at. pct Ta films at 900 °C for 1 hour resulted in the formation of body-centered-cubic (bcc) Ta particles (>50-nm diameter) in addition to the much smaller fcc Ta particles. Annealing the low and high Ta composition films at 900 °C for as long as 100 hours produced no observed change in either the Cu matrix grain size or the size and distribution of the fcc and bcc Ta particles. Microhardness and nanoindentation mechanical property evaluations of bulk hot-pressed materials indicated that the high strengths of the composites were unchanged, even after annealing for 100 hours at 900 °C.     

Some physicomechanical properties of ZrC-NbC-MoC1−x alloys

Conclusions Standard programs have been developed for the processing and geometric representation of data for systems consisting of more than two components. Composition—property surfaces have been constructed for the modulus of normal elasticity, microhardness, melting point, and lattice constant over the whole field of compositions of MoC_1–x-NbC-ZrC solid solutions. It is shown that the calculated polynomials match closely the actual response surfaces. The error involved in the prediction of values of properties has been calculated.Deceased.Translated from Poroshkovaya Metallurgiya, No. 12(180), pp. 76–82, December, 1977.     

Synthesis of complex carbonitrides Ti1−x WxC1−y Ny

We have studied the effect of process factors (temperature, nitrogen pressure, composition) on synthesis of carbonitrides Ti_1?xW_xC_1?yN_y from the starting components (WC, TiC, TiN) with particle size 10–12 μm. Under realistic conditions, we have determined the range of existence for homogeneous cubic carbonitrides. As the tungsten carbide content increases, the temperature needed for synthesis of homogeneous carbonitrides increases. Synthesis of complex carbonitrides occurs in two steps: via formation of titanium carbonitride followed by dissolution of WC in the latter, and by formation of the complex titanium-tungsten carbonitride. We have established that the major reason for the appearance of the W₂C phase is thermal dissociation of titanium nitride.