Abstract Aiming to improve the density of calcium hexaaluminate (CA 6 ), Zr 4+ doped CA with structural formula CaAl 11.73 ◊ 0.25 0.02 O 18.41 0 . 59 (CaAl ) was successfully synthesized at 1600℃ for 4 h in air. The effect doping on crystal structure investigated using first principle calculation, refinement combination experimental characterization. results suggest that prefers substitute Al 3+ Al3 site, which can increase lattice parameter c ‐axis and amount vacancies. average thickness is...

Two-dimensional (2D) MoB metal borides (MoB MBene) have attracted much attention due to their fascinating properties and functional applications. So far, work on the synthesis of 2D nanosheets by acid or alkaline etching MoAlB has not been very successful. It proposed that MBene may be fabricated chemical a Mo₂AlB₂ precursor, but further investigations were performed possibly difficult preparation metastable compound at high temperatures solid-state reactions. Here, we...

Abstract Novel MoAlB composites reinforced with 5–15 vol% SiC have been firstly prepared and characterized in the present study. The reinforcement is stable at a sintering temperature of 1200 °C Ar. 5 SiC/MoAlB composite exhibited improved mechanical properties enhanced oxidation resistance. A flexural strength 380 MPa Vickers hardness 12.7 GPa were achieved increased by 24% 51%, respectively, as compared those for MoAlB, indicating strengthening effect SiC. Cyclic tests 1300 10 h air showed...

Ti 3 Sn (1− x ) Al C 2 MAX phase solid solutions are successfully synthesized from different reactant mixtures. Rietveld refinement allows to carefully characterize their structures and the ocathedra trigonal prims distortion parameters as a function of content. Mechanical properties studied nanoindentation experiments dynamic resonant method. It is shown that solution hardening not operative in this system. Elastic modulus found increase SnC AlC , such result discussed terms Ti–A bond stiffness.

The HIP ing of Ti–Al–1.9TiC and Ti–Al–0.2Sn–1.8TiC reactant mixtures yields Ti 3 AlC 2 Al 0.8 Sn 0.2 C solid solutions, respectively. Rietveld refinement gives a = 3.0786 ± 0.0001 Å c 18.589 0.001 lattice parameters for 3.0837 18.621 0.002 . Furthermore, about 2–3 vol% x y intermetallics is detected in solution. intrinsic hardness, measured by nanoindention tests, 11.4 0.7 GPa 10.2 0.6 hardness values, microindentation are compared with the ones nanoindentation. It shown that nanoindentation...

MAX phase Ti 2 Al (1− x ) Sn C solid solution with = 0, 0.32, 0.57, 0.82, and 1 was synthesized by pressureless sintering of uniaxially pressed , TiC powder mixtures. Annealing in air atmosphere at 200°C–1000°C triggered a sequence oxidation reactions which reveal distinct influence composition on the process. With decreasing / ratio, characteristic temperature accelerated reaction A‐element reduced from 900°C ( 0) to 460°C 1). SnO formed temperatures significantly lower than TiO (rutile) O...

Abstract Ti 2 AlC, a MAX phase ceramic, has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon at high temperatures in air (high oxygen partial pressures). However, such repair damages vacuum or low pressure conditions remains unknown. Here, we report on behavior of AlC about 1 Pa. The experimental results showed that strength recovery depends both temperature and time. After 1400 °C for 1–4 h, healed samples exhibited recovered...

Abstract Carbonitride MXenes, such as Ti 3 CNT x , 2 C 0.5 N T and 4 (C 0.2 0.8 ) have attracted much interest in the large family of two‐dimensional (2D) nanomaterials. Like their carbide MXene counterparts, nanolayered structure functional groups endow carbonitride MXenes with an attractive combination physical chemical properties. More interestingly, replacement by changes lattice parameters electron distribution due to greater electronegativity compared C, thus resulting significantly...

Abstract In this work, the oxidation‐induced crack healing of Al 2 O 3 containing 20 vol.% Ti AlC MAX phase inclusions as particles was studied. The oxidation kinetics having an average diameter about 10 μm studied via thermogravimetry and/or differential thermal analysis. Surface cracks 80 long and 0.5 wide were introduced into composite by Vickers indentation. After annealing in air at high temperatures, filled with stable oxides a result decomposition particles. Crack 800, 900, 1000°C for...

In this study, we report on the compressive behavior of Ti 3 AlC 2 and Al 0.8 Sn 0.2 C MAX phases at room temperature. We found that these two could be classified as Kinking Nonlinear Elastic (KNE) solids. The cyclic stress–strain loops for are typical hysteretic fully reversible. At failure, both compositions fracture in shear with maximum stresses 545 MPa 839 . Consequently, macroshear τ c , 185 242 respectively. addition to grain size effects, presence a ductile x y intermetallic...

Oxidation induced crack healing of Al 2 O 3 composites loaded with a MAX phase based repair filler (Ti 0.5 Sn C) was examined. The fracture strength 20 vol% containing artificial indent cracks recovered fully to the level virgin material upon isothermal annealing in air atmosphere after 48 h at 700°C and 900°C. SEM ‐ EBSD analysis microstructure indicates two different oxidation reaction regimes govern filling: near surface SnO , TiO were formed whereas deeply inside metallic detected....

Highly pure Al4SiC4 powders were prepared by carbothermic reduction at 2173 K using Al2O3, SiO2, and graphite as raw materials. The obtained owned hexagonal plate-like grains with a diameter of about 200–300 μm thickness 2–6 μm. Based on the experimental results, reaction formation grain evolution mechanisms determined from thermodynamic first-principles calculations. results indicated that synthesis consisted two parts, i.e., solid–solid reactions initially followed complex gas–solid...

Aluminum nitride (AlN) with a combination of very high thermal conductivity and excellent electrical insulation properties exhibits wide applications. However, it is quite sensitive to moist environment hydrolyzes slowly in water. In this work, density functional theory was adopted examine the atomistic reaction mechanism on wurtzite AlN(0001) surface. The results indicate that water molecules are preferentially adsorbed at top site decomposition H2O into OH H surface occurs spontaneously...

New types of microwave absorption (MA) materials are urgently demanded in military radars and communication satellites working the frequency 8–12 GHz (X band) 12–18 (Ku band). However, it remains a challenge to make material completely satisfy MA requirements whole bands. Here, two-dimensional (2D) Ti3CNTx nanolayered flakes were produced by HF etching Ti3AlCN precursor exhibited an attractive performance X Ku The minimum reflection loss (RL) was −41.36 dB at 11.76 with sample thickness 1.94...