Titanium Diboride–Tungsten Diboride Solid Solutions Formed by Induction‐Field‐Activated Combustion Synthesis

Abstract

Solid solutions of titanium diboride–tungsten diboride (TiB2–WB2) were synthesized by induction‐field‐activated combustion synthesis (IFACS) using elemental reactants. In sharp contrast to conventional methods, solid solutions could be formed by the IFACS method within a very short time, ∼2 min. Solutions with compositions ranging from 40–60 mol% WB2 were synthesized with a stoichiometric ratio (Ti + W)/B =½; however, samples with excess boron were also made to counter the loss of boron by evaporation. The dependence of the lattice constants of the resulting solid solutions on composition was determined. The “a” parameter decreased only slightly with an increase in the WB2 content, whereas the “c” parameter exhibited a significant decrease over the range 40–60 mol% WB2. Solid‐solution powders formed by the IFACS method were subsequently sintered in a spark plasma sintering (SPS) apparatus. After 10 min at 1800°C, the samples densified to relative density 86%. XRD analysis showed the presence of only the solid‐solution phase.

Effect of Ni and Co Additives on Phase Decomposition in TiB2–WB2 Solid Solutions Formed by Induction Field Activated Combustion Synthesis

“…Powders of titanium, tungsten, and boron were weighed out in mole ratios of Ti/W/B ϭ 1/1/4.6 to give a composition of (Ti,W)B 2.3 and were dry-mixed in an automatic agate mortar for 1 h. Excess boron was used because of previous experience indicating the loss of this element (due to the evaporation of its oxide) during synthesis. 7 The mixed powders were packed into a cylindrical carbon sheet, ϳ0.7 mm in thickness and 40 mm in diameter and 10 mm long. The packing density of each powder compact was about 50%.…”

“…That crucible was then placed in the IFACS equipment. 7 Details of the experimental setup were provided in recent publications. [7][8][9] The reaction in the sample was initiated by induction under the conditions of 85 V, 170 A, 70 kHz, and 120 s. The powders of the resulting TiB 2 -WB 2 solid solutions were crushed by ball milling using a silicon nitride jar and balls until an average particle size of 2 m was obtained.…”

“…Temperatures were measured with a W-5%Re/W-25%Re thermocouple using a data acquisition recorder as described in previous publications. [7][8][9] After the annealing period, the products were analyzed by X-ray diffraction (RAD-C system, Rigaku of Tokyo, Inc., Tokyo, Japan) using CuK␣ radiation. Microstructural and elemental analyses were conducted on cross sections of the annealed samples using scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) (JSM-330, JEOL of Tokyo, Inc., Tokyo, Japan).…”

“…3,4 In a recent investigation, the present authors prepared TiB 2 -WB 2 solid solutions by induction field activated combustion synthesis (IFACS), again using elemental reactants. It was shown that solid solutions could be synthesized in about 2 min, 7 in sharp contrast to the long annealing time required in the conventional (furnace) method. In the IFACS method rapid heating is achieved by the induced current, 8,9 which has been shown to be effective in the synthesis of compounds with low heats of formation, a decided advantage over conventional combustion synthesis.…”

Eco-Fabrication Process and Thermoelectric Properties of β-FeSi₂

“…In the present study, β-FeSi2 was produced by a rapid eco-process involving induction-field activated combustion synthesis / static pseudo-isostatic compaction (IFACS/SPIC) [10][11][12][13] and annealing. IFACS offers many advantages, such as short synthesis time (on the order of seconds to minutes), low power (max.…”