Direct Nitridation Research Articles

Synthesis and characterization of titanium oxynitride catalyst via direct ammonia nitridation of titanium polyacrylate for oxygen reduction reaction

A titanium oxynitride catalyst for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells was synthesized through the direct ammonia nitridation of titanium complexes. Titanium polyacrylate was employed as the catalyst precursor, and the effect of the calcination temperature between 600 and 1000 °C on the catalyst structure was studied. The catalysts were characterized via X-ray diffraction, X-ray absorption spectroscopy, transmission electron microscopy, cyclic voltammetry, and powder electrical resistivity measurements. The formation of titanium oxynitride particles and deposited carbon was observed for all the samples; however, significant variations in the catalyst structure and catalytic activity were also observed. With an increase in the calcination temperature, nitridation of titanium oxynitride progressed, and the conductivity of the catalyst powder increased. The highest rest potential and ORR current density were achieved with calcination at 800 °C. Importantly, the results suggest that maintaining an optimal nitrogen doping level within the catalyst particles, along with ensuring the formation of electroconductive deposited carbon, is essential for achieving a high ORR current. This work introduces the direct ammonia nitridation of metal complexes as a promising process for designing metal oxynitride catalysts.

Localized nitride strategy to construct interfacial and electronic modulated WO3/WN nanoparticles for superior lithium-ion storage

The interfacial effect is important for the tungsten trioxide (WO3)-based anode to achieve superior lithium-ion storage performance. Herein, the interfacial effect was constructed by in-situ surface direct nitridation reaction at 600 ℃ for 30 min of the as-synthesis WO3 nanoparticles (WO3/WN). X-ray photoelectron spectroscopy (XPS) analysis confirms evident chemical interaction between WO3 and WN via the interfacial covalent bond (WON). This WO3/WN anode shows a distinct interfacial effect for an efficient interatomic electron migration. Electrochemical kinetic analysis shows enhanced pseudocapacitance contribution. The galvanostatic intermittent titration technique (GITT) result demonstrates improved charge transfer kinetics. Ex-situ X-ray diffraction (XRD) analysis reveals the reversible oxidation and reduction reaction of the WO3/WN anode. The density functional theory (DFT) result shows that the evident interfacial bonding effect can enhance the electrochemical reaction kinetics of the WO3/WN anode. The discharge capacity can reach up to 546.9 mA h g−1 at 0.1 A g−1 after 200 cycles. After 2000 cycles, the capacity retention is approximately 85.97 % at 1.0 A g−1. In addition, the WO3/WN full cell (LiFePO4/C//WO3/WN) demonstrates excellent rate capability and capacity retention ratio. This in-situ surface nitridation strategy is an effective solution for designing an oxide-based anode with good electrochemical performance and beyond.

EFFECT OF GAS NITRIDING PARAMETERS ON THE MICRO-HARDNESS OF HIGH-SPEED STEEL-CUTTING TOOLS

In this study, the nitriding parameters, such as nitriding time, nitrogen flow, and cooling type, were regularly modified to assess the effects of each on the microhardness of tools constructed of high-speed steel designed for commercial usage. The nitriding temperature was maintained at 670 °С for all of the tools. The tools were designed to measure microhardness. With a maximum value of 2000 HV at a time of 42 hours, direct nitriding with a nitrogen flow of 20 l/h and air cooling exhibits an apparent relationship between nitriding time and microhardness. The maximum microhardness value (1555.44 HV) was achieved by quenching after nitriding for 72 hours with a nitrogen flow rate of 20 l/h. The relationship between nitrogen flow and microhardness is semi-direct for direct nitriding at a nitriding duration of 30 hours and furnace cooling, with a maximum value of 1566.65 HV at a nitrogen flow of 110 l/h. The maximum microhardness was 2000 HV, with a 1.63% increase. The microstructure of the tools was improved by increasing the concentration of iron nitride in the ferrite cell, which means that the gas nitriding process increases the efficiency of cutting operations and reduces workpiece material surface roughness, based on the results of this study, it is advised to use high-purity nitrogen rather than ammonia. high-purity nitrogen gives better results than traditional nitriding using ammonia gas.

Low-temperature synthesis of dense Si-based nitride ceramics for solar thermal storage: Role of cordierite as sintering additive

Direct nitridation method was used to prepare dense Si-based ceramics for solar thermal storage, and the effect of cordierite as sintering additive on the sintering behaviors of the ceramics was studied. The influence priority between densification and nitride content on the properties of thermal storage ceramics was discussed. Cordierite exhibited a good capability of promoting densification, and the densification temperature could reach 1500 °C. The liquid formed by cordierite helped to construct an interlocking structure of well-grown Si2N2O flakes. Results of hot stage microscopy and DTA indicated that the endothermic silicothermic reaction between Si and cordierite proceeded at 1440–1460 °C, and released SiO gas. The SiO gas inhibited the densification, but resulted in the low-temperature synthesis of nano-sized Si3N4 whiskers. Samples added with more cordierite showed the cost-effective merits as the smaller costs of raw materials, lower densification temperature, higher thermal conductivity (1.72 W m−1 K−1 deviation), and higher bending strength (34.3–68.1 MPa deviations), compared with the samples having the larger nitride content. Densification by adding cordierite as sintering additive showed the priority on the properties of thermal storage ceramics than increasing the nitride content.

Advancing sintering and matrix-reinforcement interaction in Al/AlN metal matrix composites through use of novel AlN reinforcement

Demand for energy-efficient transportation has led to increased use of lightweight aluminium alloys due to their exceptional strength-to-weight. Meanwhile, aluminium-based metal matrix composites (MMCs) are being developed to enhance wear resistance and strength. However, traditional ceramic reinforcements often have poor bonding with the matrix, compromising performance. Here, we demonstrate the use of a novel ex-situ AlN reinforcement powder to enhance sintering and interfacial bonding for powder metallurgy preparation of Al/AlN MMCs. We compared two series of Al/AlN MMCs featuring 10 vol.% ex-situ AlN reinforcement, one prepared using commercial AlN powder, and the other using our novel AlN reinforcement prepared by low temperature direct nitridation of Al powder. Metallic Al contained in the synthesized reinforcement significantly improved interfacial adhesion between matrix and reinforcement and enhanced densification during sintering. This resulted in a substantial improvement in tensile mechanical properties, with an 11.5% increase in ultimate tensile strength and almost five-fold improvement in ductility compared to composites prepared using the conventional ceramic AlN reinforcement. This study provides a strategy for powder metallurgy production of advanced Al/AlN MMCs with superior physical and mechanical properties.

Si3N4 preparation from photovoltaic kerf loss silicon waste by copper collaborative nitriding method

In this work, Si3N4 powders were prepared by collaborative direct nitriding method from photovoltaic kerf loss silicon waste. The catalytic effect of copper (Cu) on the direct nitriding reaction of photovoltaic Si waste and the morphologies of the nitriding products were investigated. The quantitative analysis of XRD results and thermogravimetric results demonstrate that Cu significantly reduces the initial nitriding temperature, and Cu has a positive effect on the nitriding of silicon waste. At 1300 °C, the sample without Cu had almost no nitriding reaction, while the total conversion rate of kerf loss waste Si was 100 %, and the yield of (α+β) Si3N4 was up to 79.2 % with 8 wt% Cu additive. The thermodynamic analysis of the Si-O-N-Cu and nitriding process was carried out by FactSage software. Moreover, the morphologies of the nitride products were observed by SEM. The addition of copper promoted the generation of Si3N4 nanorods, and the number and diameter of α-Si3N4 nanorods increased with the increase in copper content. Three reaction mechanisms of Si nitridation were discussed. This work provides a feasible method to reuse and recycle the kerf lost silicon waste.

Lithium‐Mediated Nitrogen Reduction for Ammonia Synthesis: Reviewing the Gap between Continuous Electrolytic Cells and Stepwise Processes through Galvanic Li─N2 Cells

AbstractElectrochemical N2 reduction reaction (E‐NRR) has recently gained increasing interest within the scientific community, due to the ongoing energy crisis and pursuit of process sustainability. In this scenario, emerging lithium‐mediated (Li‐m) strategies are obtaining promising Faradaic efficiency (FE) and NH3 production rate values. In this work, the Li‐m scenarios are classified and explained toward a more sustainable process. Continuous processes, with a lithium salt and a proton donor in an electrolytic cell, are analyzed and compared with stepwise pathways. Different parameters are summarized in relation to the system stability, for which the importance of a tailored solid electrolyte interphase (SEI) layer emerged. Among stepwise processes, the thermochemical direct nitridation of lithium is discussed together with the recently developed Galvanic Li─N2 cell strategy.

Effect of Ti-Si-Fe alloy on the nitriding behavior of Si powder

Adding Ti-Si-Fe alloy to Si powder reduced the complete nitriding temperature of Si from 1450 °C to 1300 °C, greatly reducing the nitriding temperature of Si powder and the formation temperature of Si3N4 whiskers. At low temperature, Fe in Ti-Si-Fe alloy damaged the SiO2 film on the surface of Si and produced SiO (g), which was conducive for the indirect and direct nitridation of Si. The density functional theory (DFT) calculation results showed that the energy levels of SiO (g) molecules adsorbed by Fe broadened and moved towards lower energy levels, resulting in a decrease in the bonding strength and an increase in reaction activity of SiO (g) molecules. It was beneficial for the indirect nitridation reaction of 3SiO (g)+2N2 (g)=Si3N4 (s)+3/2O2 (g), and promoted the formation of α-Si3N4 whisker. The liquid phase formed by increasing temperature and Ti-Si-Fe alloy addition promoted the direct nitridation of Si. The activation energy of TiSi2 and Ti-Si-Fe alloy nitridation was 78.42 (KJ/mol) and 14.97 (KJ/mol), respectively. The nitridation of Ti-Si-Fe alloy was easier, and the pores and cracks generated by Ti5Si3 and TiSi2 step-by-step nitridation at low temperature in Ti-Si-Fe alloy provided pore channels for N2 transport and sufficient nitrogen for Si nitridation.

Strong green up-conversion luminescence and optical thermometry of Ho3+/Yb3+ Co-doped AlN submicron towers

Rare-earth (RE) doped aluminum nitride (AlN) holds great promise for integrated optoelectronic devices. Here, the Ho and Yb co-doped AlN (AlN:Ho3+/Yb3+) submicron towers were prepared by a direct nitridation route. XRD, Raman, XPS and EDS studies showed successful doping of Ho and Yb ions into AlN. SEM images show that the submicron towers have an interesting layered structure by layer-by-layer stacking of hexagonal AlN nanosheets. Under excitation at 980 nm, AlN:Ho3+/Yb3+ submicron towers exhibit up-conversion (UC) luminescence at 540, 550, 659, and 762 nm, which are due to Ho3+/Yb3+ system from 5F4, 5S2→5I8, 5F5→5I8, and 5F4, 5S2→5I7 respectively. Based on the intensity ratio and decay lifetime of UC luminescence, the optical temperature sensing characteristics are investigated from 298 K to 548 K. The maximum relative sensitivities associated with the intensity ratio of I540, 550 and I659 and decay lifetime of 659 nm are as high as 2.73% K−1 and 0.43% K−1, respectively. This work broadens the optoelectronic properties of RE doped AlN.

Direct synthesis of porous aluminum nitride foams for enhancing heat transfer and anti-leakage performance of phase change materials

Organic phase change materials (PCMs) suffer from low thermal conductivity and easy leakage, which limit their application in heat storage and thermal management. In this work, porous AlN skeletons were synthesized to solve these problems of paraffin PCM. Using Al powders as raw material, porous AlN skeletons were prepared through the ice-templated method and the direct nitridation reaction. The skeletons were impregnated with paraffin to prepare phase change composites (PCCs). The thermal conductivity of the PCC with 55.6 wt% AlN reaches 9.1 W m−1 K−1 in the axial direction, which is 4550 % of paraffin. This PCC retains a high enthalpy of 105 J g−1 and has good thermal stability. Moreover, the porous AlN skeletons can effectively absorb paraffin so that all PCCs maintain a stable shape. This study provides a simple and efficient method to synthesize porous AlN and to solve the heat conduction and leakage issues of PCMs.

Study on reaction mechanism for the synthesis of vanadium nitride by carbothermic reduction nitridation method

Vanadium nitride (VN), as a typical transition metal nitride, has widespread applications in various fields due to its high melting point, high hardness, and excellent thermal and chemical stability. In this study, VN was synthesized through the carbon thermal reduction nitridation method using V2O3 as the main material, and the reaction mechanism was thoroughly examined. Thermodynamic analysis, coupled with thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), revealed that the reaction mechanism was not simply a direct nitridation process nor a two-step coupling of reduction and carburization. Instead, it was the result of multiple reaction mechanisms working in conjunction. Direct nitridation of V2O3 occurred throughout the entire reaction process, while indirect nitridation of VO and VC also occurred with the variation of temperature. A kinetic model was constructed based on the material thermal weight loss curve and revealed that in the carbothermal reduction nitridation system of V2O3, the solid phase reaction followed a three-dimensional diffusion model, with an activation energy of 160.244 kJ/mol, while the gas phase reaction with the solid phase followed a one-dimensional interface model, with an activation energy of 169.015 kJ/mol.

AlON transparent ceramics from powders synthesized by improved direct nitridation

Single-phase aluminum oxynitride (AlON) powders were synthesized by improved direct nitridation (DN). The improved DN method is to obtain high quality powder by adding high nitrogen pressure on the basis of ordinary DN method. Compared with the ordinary DN method, the average particle size of the synthesized powder is reduced by about 20 μm, the morphology tends to be spherical and the sintering activity is higher. Using different particle size α-Al2O3 precursor, a modified DN method was adopted to synthesize spherical, good dispersibility and fine AlON powders. The influence of particle size of raw material α-Al2O3 on sintering properties was investigated. Transparent AlON ceramics with dimensions of φ 103mm × 3 mm with in-line transmittance greater than 80%were fabricated by pressureless sintering from above AlON powders. In addition, the effects of different nitrogen pressure on the morphology, particle size distribution and average particle size of synthetic powder were investigated. On this basis, the differences between DN method and improved DN method on synthetic powder and the possible synthesis mechanism were proposed.

Cost-effective preparation of high-quality silicon nitride powders from silicon scrap through direct nitridation

This work reports a cost-effective and environmentally friendly method for preparing high-quality and highly-crystalline silicon nitride (Si3N4) powders from silicon (Si) scrap through direct nitridation. With Si scrap from semiconductor manufacturing processes being a critical and imperative global issue in recent times, an efficient methodology is essentially required to recycle it. For this purpose, ball milling parameters for Si scrap were optimized using different solvents to obtain homogeneous and fine-micron sized silicon powders for efficient nitridation. Ethanol was found to be the most effective in producing the required conditions of Si powders. Direct nitridation was performed at 1450 °C in an atmosphere of nitrogen and hydrogen gas flow to prepare Si3N4 powders. Various characterization techniques were used to analyze particle sizes, phase compositions, and morphologies of raw Si scrap, ball-milled Si powders, and Si3N4 powders. Results indicated that the nitridation reaction resulted in 90.1% conversion of Si into Si3N4 and the α-Si3N4 phase accounted for 85% of the total Si3N4 produced. This study provides a fundamental perspective from both industrial and environmental standpoints on the recycle of Si waste and production of cost-effective and high-quality Si3N4 powders. This novel approach of using Si scrap as a silicon source for Si3N4 powder preparation has the potential to significantly reduce the large volumes of Si waste generated from semiconductor industries.

The impurity centers in (N,F)-substituted barium titanate: The preferable models and probable mechanisms of formation according to ab initio simulations

For nitrogen- and fluorine-substituted barium titanate, the different variants of mutual arrangement of defects in the lattice have been regarded. The various models of impurity centers and crystalline structure for the doped compound have been proposed. The ab initio calculations of electronic structure for each of models were performed, and for different doping strategies, the preferable models of impurity centers have been determined. It was shown that the in (N,F)-co-doped or non-stoichiometric barium titanate the pair centers “N-F” and “N-vacancy” are favorable, meanwhile, the implantation of fluorine alone prevents the formation of oxygen vacancies, and corresponding single impurity centers are expected to be formed. It was shown that the presence of fluorine atoms or oxygen vacancies in BaTiO3 lattice favors the implantation of nitrogen. A series of solid-state reactions of synthesis both ideal and (N,F)-substituted or non-stoichiometric BaTiO3 was proposed and discussed, their energies were estimated (based on the results of calculations of electronic structure), and the most energetically favorable of them were specified to be promising for the direct nitridation processes.

Crystallographic Study of Product Phases of Carbothermic Reduction and Nitridation of Hafnium Dioxide.

Details of the carbothermic reduction/nitridation to synthesize hafnium nitride (HfN) and hafnium carbide (HfC) are scarce in the literature. Therefore, this current study was carried out to evaluate two pathways for synthesizing these two refractory materials: direct nitridation and carbothermic reduction/nitridation. Two mixtures of hafnium dioxide and carbon with C/HfO2 molar ratios of 2.15 and 3.1 were nitridized directly using flowing nitrogen gas at elevated temperatures (1300-1700 °C). The 3.1 C/HfO2 molar ratio mixture was also carbothermically reduced under flowing argon gas to synthesize HfC, which was converted into HfN by introducing a nitridation step under both N2(g) and N2(g)-10% H2(g). X-ray diffraction results showed the formation of HfN at 1300 and 1400 °C and HfC1-yNy at ≥1400 °C under direct nitridation of samples using a C/HfO2 molar ratio of 2.15. These phase analysis data together with lower lattice strain and greater crystallite sizes of HfC1-yNy that formed at higher temperatures suggested that the HfC1-yNy phase is preferred over HfN at those temperatures. Carbothermic reduction of 3.1 C/HfO2 molar ratio samples under an inert atmosphere produced single-phased HfC with no significant levels of dissolved oxygen. Carbothermic reduction nitridation made two phases of different carbon levels (HfC1-yNy and HfC1-y'Ny', where y' < y), while direct nitridation produced a single HfC1-yNy phase under both N2 and N2-10% H2 cover gas environments.

Ultra-narrow deep-red emitting AlN:Sm2+phosphor with nano-branched construct for wide color gamut backlight display and high-pressure sensing applications

Rare-earth (RE) doped AlN are excellent candidate materials for electroluminescent devices, full color displays and white lighting technology. In this paper, a deep red Sm2+ doped AlN (AlN:Sm2+) phosphor was synthesized for the first time by a one-step direct nitridation method. Detailed XRD and EDS studies show the presence of samarium (Sm) ions the AlN, and XPS measurements indicate Sm ions are divalent. SEM and TEM studies show that the AlN:Sm2+ have a branched nanostructure, consisting of a primary stem and secondary short nano-branches. AlN:Sm2+ phosphor has a broad and strong excitation bands in the range of 300–600 nm, ultra-narrow deep red emission at 686 nm, near unity color purity, and good thermal stability (78.2% at 413 K). A blue-pumped warm white light emitting diode with high color rendering index (Ra∼87.5) and low correlated color temperature (CCT∼4875 K) was fabricated. Moreover, a super-wide color gamut (117.6% of the NTSC) can be achieved by using AlN:Sm2+ as the red component. Furthermore, photoluminescence (PL) and Raman spectra of AlN:Sm2+ were studied under hydrostatic pressure up to 25 GPa. The shift of the 5D0→7F0 emission band (dλ/dP≈0.13 nm/GPa) and the decrease of PL intensity ratio (5D0→7F0/5D0→7F1, dIR(0/1)/dP≈−5.6%/GPa) with applied pressure can be used for optical pressure sensor. Raman spectroscopy revealed a phase transition of AlN:Sm2+ from wurtzite to rocksalt phase at 19.9 GPa. The large doping of Sm2+ ions and unique intrinsic geometry in branched nanostructure co-affect its compressibility and structural stability under high pressure. The results indicate that AlN:Sm2+ phosphor has promising applications in backlight displays and optical pressure sensors due to their excellent luminescent properties.

Synthesis of spherical-like β-Si3N4 powder by direct nitridation of silicon saw dust

ABSTRACT Spherical-like β-phase silicon nitride (β-Si3N4) powder has been synthesized by direct nitridation of silicon saw dust recovered from the photovoltaic industry in ammonia gas (NH3) at 1300°C with calcium fluoride (CaF2) as additive. The X-ray diffraction (XRD) analysis indicates that the formation of β-Si3N4 is enhanced and accelerated in NH3 compared to nitrogen (N2). The scanning electron microscope (SEM) examination shows that, compared with N2, NH3 contributes to the formation of spherical-like particles, and all irregular silicon particles are transformed into spherical-like β-Si3N4 particles in the NH3 atmosphere. These results indicate that the NH3 atmosphere is conducive to the formation of submicron spherical-like β-Si3N4 particles. A complete submicron spherical-like Si3N4 powder with 93.12 wt% β phase has been synthesized by direct nitridation of silicon saw dust assisted with 5 wt% CaF2 additives in NH3. The mechanism for the formation of the spherical-like β-Si3N4 powder has also been discussed.

Synthesis of Aluminum Nitride Using Sodium Aluminate as Aluminum Source

At present, the carbothermal reduction and nitridation process is an important method for the large-scale preparation of aluminum nitride powder in industry, but the tremendous energy consumption caused by long-term high temperatures seriously restricts its practical application. To solve this problem, the (NaAlO2+C) mixture with a mole ratio of NaAlO2:C = 1:3 was prepared based on sodium aluminate and carbon black which has been ball milled with anhydrous ethanol as a grinding liquid. The crystal structure evolution and nitridation reaction behavior of sodium aluminate at 800–1600 °C under a nitrogen atmosphere in the presence of carbon were systematically studied employing XRD, SEM, and ICP-MS. The results showed that: high energy θ-Al2O3, η-Al2O3 can be excited by heating sodium aluminate to 1400 °C under a nitrogen atmosphere in the presence of carbon. The transformation process between sodium aluminate and aluminum nitride is carried out via the direct nitridation of θ-Al2O3, η-Al2O3. Benefiting from the direct nitridation of η-Al2O3 and θ-Al2O3, high-purity aluminum nitride powder with a particle size of 0.50 ± 0.18 μm was synthesized at 1400 °C. This work provides a new path for reduced energy consumption in the aluminum nitride industry.

Effect of powders on aluminum nitride components fabricated by PIM

Powder selection is essential to the success of powder injection molding (PIM). In this study, aluminum nitride (AlN) powder synthesized through carbon-thermal (C-R) reduction and direct nitridation (DN) were used as the raw material. These two kinds of powder were mixed with wax-based binder and the rheological properties of AlN feedstocks were examined. Then the green parts were fabricated by powder injection molding and sintered after solvent and thermal debinding. Finally, the appearance, microstructure and thermal conductivity of sintered AlN were inspected. It was found that the C-R powder has higher critical solid loading (60 vol%) than DN powder (58 vol%). Feedstocks viscosity decreased when the shear rate increased, indicating the presence of non-Newtonian pseudoplastic flow. The C-R powder also has better rheology properties with lower viscosity, higher melt flow rate, higher shear thinning, and higher activation energy. As for the performance after short-time sintering, the thermal conductivity of C-R AlN is 183 W·m−1·k−1 while the value of DN AlN is 130 W·m−1·k−1, and the bending strength of C-R AlN is 363 MPa while that of DN AlN is only 320 MPa.

Impacts of Temperature and Time on Direct Nitridation of Aluminium Powders for Preparation of AlN Reinforcement

Aluminium nitride (AlN) is an important technical ceramic with outstanding strength and thermal conductivity that has important applications for advanced heat sink materials and as a reinforcement for metal-based composites. In this study, we report a novel, straightforward and low-cost method to prepare AlN powder using a vacuum tube furnace for the direct nitridation of loose aluminium powder at low temperatures (down to 500 ∘C) under flowing high-purity nitrogen. Small amounts of magnesium powder (1 wt.%), combined with aluminium, promote nitridation. Here, we characterise the effects of time (up to 12 h) and temperature (490 to 560 ∘C) on nitridation with the aim to establish an effective regimen for the controlled synthesis of an aluminium nitride reinforcement powder for the production of metal matrix composites. The extent of nitridation and the morphology of the reaction products were assessed using scanning electron microscopy and X-ray diffraction analyses. AlN was detected for all nitriding temperatures ≥ 500 ∘C, with the highest yields of 80% to 85% obtained at 530 ∘C for times ≥ 1 h. At this temperature, nitridation proceeded rapidly, and there was extensive agglomeration of the reaction products making it difficult to reprocess into powder. At lower temperatures around 510 ∘C, a relatively high proportion of AlN was attained (>73% after 6 h) while retaining excellent friability so that it could be manually reprocessed to powder. The synthesised reinforcement consisted of micro- or nano-crystalline AlN comingled with metallic aluminium. The ratio of AlN and metallic aluminium can be readily controlled by varying the nitriding temperature. This provides a flexible and accessible method for the production of AlN-reinforcement powders suited to the production of metal matrix composites.