Amorphouslike Diffraction Pattern in Solid Metallic Titanium

Abstract

Amorphouslike diffraction patterns of solid elemental titanium have been detected under high pressure and high temperature using in situ energy-dispersive x-ray diffraction and a multianvil press. The onset pressure and the temperature of formation of amorphous titanium is found to be close to the --! triple point in the P-T phase diagram. Amorphous Ti has been found to be thermally stable up to 1250 C for at least 3 min at some pressures. By analyzing the conditions for producing amorphous elemental Zr and Ti, we observed a multi-phase-point amorphization phenomenon for preparing single-element bulk amorphous metals. The results reported may open a new way to preparing single-element bulk amorphous metals with a high thermal stability.

Nucleation mechanism for hcp→bcc phase transformation in shock-compressed Zr

“…5(a)), shows the presence of amorphous intermediate state. Experimental observations are beginning to support our findings, for example, amorphous-like structures have been observed in previous quasi-static DAC experimental measurements of pure Zr[21,38].…”

IR and near IR laser ablative deposition of amorphous titanium coats containing nanocrystalline grains of titanium and titanium suboxides

“…Thus, amorphous-like energy-dispersive X-ray diffraction patterns (absence of Bragg spots) were earlier reported for solid hightemperature/high pressure zirconium and titanium [7,8], but later reconciled with rapidly grown crystalline grains [9] confirmed by intense Bragg spots in two-dimensional angle-dispersive X-ray diffraction spectra. Other studies on amorphous titanium concerned molecular dynamics simulation of crystallization [10] and amorphization of titanium by using C + , O + and Cr + ion implantation [11], oxygen-induced ball milling [12] and cryorolling combined with surface mechanical attrition treatment [13].…”

“…The deposited diffraction-less Ti coats are stable at ambient temperatures for extended periods of time (more than a year). This is very different from the amorphous-like Ti phases observed at high pressures and temperatures which rapidly revert to the crystalline phase upon cooling to room temperature [8]. The base pressure during the present ablative conditions being by 2 orders of magnitude lower than in our previous experiments [31] should lead to a much smaller in situ formation of Ti suboxides due to less air leakage in the course of the ablative deposition process.…”

Effect of Mechanical Milling and Cold Pressing on Co Powder

“…Amorphization in nonmetallic elements, such as gallium [19], silicon [21], germanium [22], and selenium [23], is easily achievable. However, some studies reported amorphous phases in metallic titanium [24], nickel [25], and cobalt [26,27] produced via nonequilibrium processing. Among the nonequilibrium techniques, mechanical milling (MM) is a well-known process for producing a wide range of novel materials with unique properties.…”