In this work, Al-Mn-Si and TiC-TiB2/Al-Mn-Si strips were prepared by vertical-type twin-roll casting (TRC), and the effect of TiC-TiB2 nanoparticles (NPs) on the microstructure and mechanical ...properties of TRC Al-Mn-Si strips were studied. The TRC strips had the characteristics of coarse grains near the surface and fine grains in the center. The introduction of NPs resulted in the formation of uniform and fine grain structures due to the grain refinement effect of NPs. The refining effect on the surface grains was much greater than that on the central grains because the larger thermal undercooling of the melt at the surface led to the improvement of the nucleation efficiency of NPs. TiC-TiB2 particles could eliminate the central segregation of TRC Al-Mn-Si strips due to the control of solute diffusion by the uniform and fine grain structures, thereby reducing α-Al(Mn, Fe)Si formation in the central region. The mechanical properties of the TRC Al-Mn-Si strips were improved with the introduction of NPs. The yield strength at room temperature was increased from 79.0 MPa to 92.9 MPa, and the uniform elongation was increased from 7.2% to 10.1%, due to the fewer eutectic α-Al(Mn, Fe)Si, refined precipitates and grain structures caused by the addition of the TiC-TiB2 particles.
•The TRC strips had the characteristics of coarse grains near the surface and fine grains in the center.•The refining effect on the surface grains was much greater than that on the central grains of the TRC strips.•TiC-TiB2 particles could eliminate the central segregation of TRC Al-Mn-Si strips.•The introduction of TiC-TiB2 particles could improve the mechanical properties of the TRC Al-Mn-Si strips.
An efficient method for in-situ fabrication of a three-dimensional framework based on heterogeneous TiC–TiB2 materials with different B4C content has been reported in the present study. ...Interpenetrating TiC–TiB2/steel composites were subsequently prepared by infiltrating molten steel into TiC–TiB2 framework. The XRD and SEM analyses confirmed that three-dimensional ceramics framework mainly consisted of heterogeneous TiC–TiB2 phases with the ceramic particles closely connected with each other. TiC–TiB2 ceramics framework exhibited a high porosity in the range 87.11%–95.95% and low bulk density of 0.17–0.22 g/cm3. The sample with ceramic framework containing 20 wt% B4C exhibited the strongly continuous microstructure, whereas the sample with ceramic framework containing 25 wt% B4C had the weakly continuous framework. The Vickers hardness and fracture toughness in the composites reached 284.5 HV and 23.7 MPa m1/2, respectively. An optimal TiC: TiB2 mass ratio of 37:55 could effectively inhibit the decomposition of TiB2 in the molten steel. Inspecting the fracture surface, the dominated fracture modes was noted to be the quasi-cleavage and trans-granular dimple fracture, which could be attributed to novel three-dimensional bi-continuous structure formed between ceramic framework and steel substrate.
In this research, the mechanical properties and microstructure of the Al matrix composites reinforced with TiC + TiB2 particles (in contents of 10, 20, 30 and 40 vol%.) were investigated. The samples ...were prepared by mechanical alloying and spark plasma sintering methods under the pressure of 50 MPa and sintering temperature of 465 °C for holding time of 15 min. The XRD patterns showed the formation of TiC and TiB2 compounds from Ti and B4C initial powders and also demonstrated that the powders obtained from the ball milling process did not contain any additional compounds or impurities. The SEM images revealed the homogeneous distribution of particles (TiC + TiB2) in the Al matrix. The mechanical properties, such as hardness, Young's modulus, yield, and tensile strengths were measured by the nano-indention test. Nano-indention test showed that 20 vol% of reinforcement was optimum content of improved mechanical properties, so that in the content of 20 vol%, the Vickers hardness, Young's modulus, yield, and tensile strengths were improved about 135, 45, 195 and 194%, respectively.
The aim of achieving integration of lightweight, high strength, high‐temperature resistant, and satisfactory electromagnetic (EM) wave absorption was successfully accomplished in the present study by ...synthesizing TiC–TiB2 fibers reinforced Si3N4 composites, which were pressureless sintered at 1650°C for 2 h. The preparation of TiC–TiB2 fibers was conducted through a chloride‐assisted carbothermic method. This work focused on investigating the effects of incorporating TiC–TiB2 fibers on the mechanical properties and EM wave absorption characteristics of the composites. The 30 wt% TiC–TiB2/Si3N4 composite displayed the bulk density of 1.89 g/cm3, bending strength of 93.11 ± 3.91 MPa, fracture toughness of 1.81 ± 0.10 MPa m1/2, minimum reflection loss of −38.87 dB, and effective absorption bandwidth of 1.43 GHz in the Ku‐band, respectively. The as‐synthesized TiC–TiB2/Si3N4 composites are promising candidates for EM wave absorbing load‐bearing materials due to their outstanding mechanical properties and microwave absorption properties.
(1) The preparation of TiC–TiB2/Si3N4 composites was achieved via pressureless sintering at a temperature of 1650°C for 2 h. (2) The 30 wt% TiC–TiB2/ Si3N4 composite exhibited notable characteristics with the bending strength of 93.11 ± 3.91 MPa, minimum reflection loss of −38.87 dB, and effective absorption bandwidth of 1.43 GHz in the Ku‐band. (3) This work paves the way for the preparation of composites with both satisfactory mechanical properties and electromagnetic wave absorption properties.
Incorporating and dispersing trace manipulated agents into Al alloy melt is a longstanding challenge that hinders the balance of strength-ductility in cast Al alloys. A delicate strategy of in-situ ...fabrication and effective incorporation of the tuned agents was put forward in this study to achieve a better-optimized microstructure of Al-5.5Cu alloys with superior room-temperature and high-temperature mechanical performance. The tailored microstructure effects and optimized mechanical properties under room temperature and elevated temperature (220 °C) by varying mole ratios of dispersed TiC–TiB2 particles were investigated. The in-situ TiC–TiB2 nanoparticles with the mole ratio in 1 : 2 (TiC: TiB2) performed the best microstructure tailoring capacity for Al–Cu-based alloy, which the manipulated alloys shows the most refined and homogeneous grain microstructure with a size of 40.4 μm, compared with the based Al–Cu alloy, refined by 73.8%. Also, the segregation of Cu was mitigated and after heat treatment, the transformation of θ″ → θ′ was accelerated. Thanks to the contribution of TiC–TiB2 particles, Al–Cu alloys perform excellent strength and ductility synergy both at room temperature and elevated temperature, and the strengthening mechanism was also discussed. It is believed that this work can give an optimized strategy from the in-situ synthesis, incorporation and dispersion of manipulated agents to the alloy microstructure tailoring and strength-ductility balancing.
In this work, S30432 steel containing trace TiC/TiB2 nano-particles was manufactured, and the effects of TiC/TiB2 nano-particles on the microstructure and room and high-temperature mechanical ...properties of the S30432 steel were investigated. The addition of trace TiC/TiB2 nano-particles can reduce the grain size from 19 ± 2.3 μm to 13 ± 4.5 μm. This is because the nano-particles provide efficient nucleation sites and constrain dendrite growth. Trace nano-particles can simultaneously enhance the strength and plasticity of the S30432 steel at room temperature. At high temperature of 600 °C, the S30432 steel with trace TiC/TiB2 nano-particles can still maintain high strength and plasticity. However, as the ambient temperature increases, the strength increment of the S30432 steel with trace TiC/TiB2 nano-particles decreases gradually, while the elongation increment significantly increases. The dynamic recrystallization process is promoted by the addition of nano-particles, causing an increased softening degree. Trace TiC/TiB2 nano-particles exhibit good plasticizing effect.
The evolution of the microstructure, texture and mechanical properties of the Al–Cu–Li alloy sheets by nanoscale TiC + TiB2 ceramic particles during solid solution treatment was systematically ...investigated by characterization, texture measurements and mechanical performance tests. The yield strength, tensile strength, and elongation of the A1 alloy with the addition of nanoscale TiC + TiB2 ceramic particles under T4P conditions were 312 MPa, 420 MPa, and 21.9%, respectively, which were 35.6%, 27.6%, and 2.8% higher than those of the A0 alloy, respectively. The recrystallization mechanism of both alloys was mainly the particle stimulated nucleation (PSN) mechanism, but the nanoscale TiC + TiB2 in the A1 alloy led to a stronger Zener dragging effect, which hindered the growth of CubeND nuclei, and P-oriented grains dominated. Thus, the A0 alloy sheet was dominated by CubeND components, while the A1 alloy sheet was dominated by P recrystallized grains, which led to the two alloy sheets showing opposite variation trends of the deep drawing properties with increasing solid solution treatment time. The short-time solid-solution process is more likely to provide better properties to the alloy with TiC + TiB2 added particles better properties in terms of various aspects, such as microstructure, mechanical properties, and electrical conductivity.
.•TiC–TiB2 composite coating was deposited by ESD.•Mechanisms for the formation of ultrafine grained and amorphous structure were proposed.•Friction coefficient and wear mechanisms were obviously ...influenced by the reinforced phases.•The effect of impact angle on erosion wear mechanism of the coating is elucidated.
In the present investigation, TiC–TiB2 composite coating was deposited by electrical discharge hardening onto the surface of 40Cr steel with a TiC–TiB2 composite rod as electrode. The composite coating structure and phase compositions were characterized by SEM and XRD, the hardness and its distribution along coating were measured on micro-hardness machine. Wear resistance of composite coating was evaluated on MM-200 wear experiment machine. The results suggest that the major phases of the composite coating are TiB2, TiC and Fe3C. The micro hardness distribution along depth of composite coating is inhomogeneous, the micro hardness value of the composite coating is about 4 times of the substrate. The wear mechanism of 40Cr steel is mainly attributed to micro-cutting and adhesive wear, but the wear mechanism of composite coating is mainly attributed to micro-cutting, scratch and fatigue abrasion. The results show that the change of wear mechanism between the samples because of the hard particles and higher hardness of composite coating. Compared with the substrate, wear resistance of composite coating is 5 times higher than that of the substrate, friction coefficient of the coating decreased by 0.12–0.17 under the same wear environment. The erosion mechanism of the TiC–TiB2 composite coating is ploughing and cutting at low impact angles, but it failure in fatigue cracking and spalling at high impact angles.
In situ TiC–TiB2 reinforced Al foams with excellent mechanical properties were fabricated successfully via a novel method by the combination of Ti–B4C self-propagating reaction and melt processing ...technique. The results showed that the interfacial bonding of TiB2/Al and TiC/Al was excellent and the in-situ TiC–TiB2 reinforced Al foams exhibited an superior mechanical properties and energy absorption capacity as well as uniform deformation simultaneously. Compared with pure Al foams, the compressive strength and energy absorption capacity of the in-situ TiC–TiB2 reinforced Al foams improved by about 149% and 168%, respectively.
