Structural and Phase Transformations in Titanium Alloys Induced by Ferrosilicon Alloying

Mon, 11 Nov 2024 00:00:00 +0000

The aim of this study was to investigate the structural and phase transformations in titanium alloys induced by ferrosilicon alloying and to enhance the physical and mechanical properties of titanium-based composite materials. These findings demonstrate that the use of FS65 ferroalloy as an alloying addition leads to active interaction with titanium hydride, resulting in the formation of a complex heterophase system. Using FS65 ferroalloy, boron carbide(B4C), and carbon (C) as alloying additions, the research identifies the optimal synthesis temperature and examines the resulting microstructures and phase formations. The optimal synthesis temperature was found to be 1250◦C.At this temperature, the phases TiC, TiSi, FeTi, and Ti3SiC2were observed in the system 65 TiH2– 30 FeSi – 5C (wt.%), while TiC, Ti5Si4, Fe2Ti, and TiB2were identified in the system 65 TiH2– 30 FeSi – 5 B4C (wt.%). The addition of 5% B4C resulted in a finer microstructure with grain sizes ranging from 0.5 to 5μm, compared to grain sizes of 5–10μm with the addition of 5% C. The presence of B4C also promoted the formation of TiB2. The synthesized compacts, characterized by a fine-pored, spongy structure, are easily crushed, making them suitable for use as dispersed fillers in composite materials.

Temperature-dependent analysis of charge carrier current in Al/SiO2/p-type Si MOS structures with TiN-induced traps via the Poole-Frenkel conduction mechanism using the vertical optimization method

S. Toumi, Z. Ouennoughi — Fri, 25 Oct 2024 00:00:00 +0000

In this study, we examined the Al/SiO2/p-type Si metal/oxide/semiconductor (MOS) structure across a temperature range of 303–423 K. To create intentional traps in the oxide, a 20 nm TiN layer was deposited. We analyzed the charge carrier current as a function of temperature using the Poole-Frenkel (PF) current mechanism and simultaneously extracted the five parameters (φ, Nh/e, µ, εr, and Vcorr) characterizing the PF current conduction process through the vertical optimization method (VOM), without the need for capacitance-voltage measurements or additional graphical methods. The barrier φ decreased with increasing temperature in both accumulation and inversion modes, with slopes of dφ/dT =−1.16 meV/K and−0.833 meV/K and intercepts of 3.07 eV and 3.45 eV, respectively. Carrier densities (Nh, Ne) also decreased as temperature rose, ranging from 7×1018–5×1010 cm−3 in accumulation mode and 6.5×1018–7.98×1016 cm−3 in inversion mode, indicating a more pronounced PF current mechanism in accumulation mode. Hole mobility (µh) remained significant up to 363 K but decreased sharply at higher temperatures, whereas electron mobility (µe) remained higher. The relative permittivity εr decreased with increasing temperature, indicating greater SiO2 polarization at lower temperatures. The voltage correction Vcorr varied with temperature, decreasing in accumulation mode by 1 Vcorr−acc = −1.33 V and increasing in inversion mode by 1 Vcorr−inv = 1.03 V. The oxide voltage correction at T = 0 K was found to be 2.606 V for holes (in accumulation) and −2.302 V for electrons (in inversion). The study concludes that trapping and detrapping mechanisms are more significant for holes in accumulation mode than for electrons in inversion mode. Consequently, the p-type MOS with PF leakage current is unsuitable for technological applications, while the n-type MOS shows promise, even at elevated temperatures, due to the less pronounced PF current mechanism.

BOHR Journal of Material Sciences and Engineering

Structural and Phase Transformations in Titanium Alloys Induced by Ferrosilicon Alloying

Temperature-dependent analysis of charge carrier current in Al/SiO2/p-type Si MOS structures with TiN-induced traps via the Poole-Frenkel conduction mechanism using the vertical optimization method