Volume Fraction Of TiB Research Articles

Fe/polymer joining via Fe/TiB2 composite structures via in-situ laser-induced reaction of Fe-Ti-B system: Effect of powder composition

Achieving strong direct joining between steel and polymers through mechanical interlocking is crucial for developing multi-material structures, particularly in the automotive and aerospace industries. This study synthesized micro-scale structures on a pure Fe substrate (simulating interstitial-free (IF) steel) for mechanical interlocking with thermoplastic parts. Numerous submillimeter-scale Fe/TiB2 composite particles were in-situ synthesized by laser scanning on the Fe-Ti-B powder mixture and well-bonded with the Fe substrate. The effects of powder composition (TiB2 volume fraction) on the morphology, microstructure, and joint strength with PA6 were investigated. A TiB2 volume fraction over 60 % was essential for the formation of the composite particles promoted by a TiB2 skeletal structure. Higher TiB2 volume fractions increased the area fraction of the composite particles and decreased the bonding ratio (adhesive) of the particles with the substrate due to poor adhesiveness at the edge of the laser-scanning line. A wider high-temperature region was generated at a higher TiB2 volume fraction, suggesting that the reaction heat to form TiB2 assisted the bonding of the particles with the substrate at the edge of the laser scanning line. The Fe/PA6 joint strength increased to approximately 30 MPa with increasing the TiB2 volume fraction to 100 % and showed a linear correlation with the product of particle area fraction and bonding ratio. A higher TiB2 volume fraction was preferable for enhancing the joint strength via the micro-scale structures synthesized by laser scanning on the Fe-Ti-B powder mixture. A combination of the micro-structuring process using a high fraction of TiB2 with advanced joining technologies will contribute to manufacturing high-strength Fe/polymer hybrid parts.

Effects of TiB Volume Fraction on the Microstructure and Mechanical Properties of TiBw/TA15 Composites with Novel Columnar Structure

Effects of TiB Volume Fraction on the Microstructure and Mechanical Properties of TiBw/TA15 Composites with Novel Columnar Structure

Formation evolution and strengthening of quasi-continuous network like TiB whiskers in the in-situ TiBw/TC21 matrix composites

In-situ TiBw reinforced TC21 matrix composites with quasi continuous network structure were prepared by low energy ball milling and hot press sintering (HPS) in this work. The microstructure, mechanical properties and strengthening mechanism of TC21 matrix composites reinforced with different volume fraction of TiB were systematically studied. In-situ TiB whiskers with quasi-network structure can significantly refine the β Phase harmony α Phase size. It is also conducive to the formation of equiaxed α-Ti. The research shows that the strength of in-situ TiBw reinforced TC21 matrix composite is significantly better than that of the monolithic TC21 alloy. For example, the YS value and UTS value of in-situ TiBw/TC21 matrix composite containing 5.1 vol% are 1170 MPa and 1268 MPa respectively, which are 34.2% and 23.3% higher than those of the monolithic TC21 alloy under the same process conditions. This paper also analyzes the reason why the theoretical YS value of the composite material is greatly different from the experimental YS value, and believes that it may be that the TiB whisker forms a network structure, which affects the smooth transfer of load from the TiB whisker to the matrix.

Architecture design and significant toughness enhancement of Ti6Al4V based composites with gradient laminate distributed TiB

Titanium Matrix Composites (TMCs) are well-known for their high specific strength and elastic modulus, however short of toughness. In the present work, in order to achieve better toughness, TiB/Ti6Al4V composites with a novel multiscale gradient-laminate network structure were fabricated via powder metallurgy method combining powder stacking process. The composites exhibit a laminated structure with gradient volume fraction of TiB on the macroscopic scale and a network structure of TiB distribution on the microscopic scale. Three-point bending tests were carried out to reveal the mechanical properties of the composites. The bending strength and fracture strain achieve 1950 MPa and 0.097 in the gradient-laminated composites, which were improved significantly compared to those in the monolithic composites. The bending toughness (148.3 × 103 kJ·m-3, represented by work of fracture during the three-point bending test) of the gradient-laminated composites is about 70% higher than that of the composites without laminated architecture. Fractography suggests that the crack deflection and prolonged crack propagation path contribute to the increase of fracture strain. The crack blunting, network microcracks and interface cracks are also beneficial to improving the bending strength and toughness.

Fracture Resistance and Crack Growth Mechanisms in Functionally Graded Ti–TiB

This paper presents the results of fracture tests and crack path observations for a layered functionally graded material (FGM) consisting of Ti and TiB phases. The composition varied in a nearly linear manner from a TiB-rich layer at the bottom to commercially pure (CP) Ti at the top. Elastic properties of the mixed phase interlayers were measured using nanoindentation testing, demonstrating a linear variation with composition. These results differ significantly from approximations calculated in previous studies using a non-linear rule-of-mixtures approach. Fracture tests were conducted on single edge notch bend [SEN(B)] specimens with the notch aligned orthogonal to the direction of the composition gradient. For this crack orientation, "average" R-curve behavior based on the J-integral was investigated to understand the mechanics of crack growth. The value of J was found to be minimal (less than 1 N/mm) below 47 pct volume fraction of TiB compared to a reported value of approximately 150 N/mm for pure Ti. These results indicate that a steeper transition to high concentrations of the metallic phase is necessary to achieve adequate fracture resistance in this metal/ceramic FGM. Observations on the specimen surface indicate crack path toughening mechanisms of this functionally graded material include crack bridging, branching, and deflection.

Effects of process parameters on the microstructure and mechanical properties of a laser micro-alloying TiB/Ti–6Al–4V titanium matrix composite

The morphology and distribution of TiB are the key factors contributing to the properties of Boron-added titanium matrix composites (TMCs) with the condition of rapid laser solidification. The processing technology called laser micro-alloying is used to prepare titanium matrix composite material Ti–6Al–4V+0.3 wt%B in this work, and the relationship between various parameters and the microstructure of laser micro-alloying is determined. The Ti–6Al–4V+0.3 wt%B alloy shows three typical distributions of TiB under three different laser power ranges: TiB is enriched along the grain boundary in the low laser power range (500–1000 W), intragranular dispersed TiB in the medium laser power range (1500–3000 W), and TiB with a quasi-continuous network structure in the high laser power range (3500–5000 W). The volume fraction of TiB shows an increasing trend with the increase of the laser power, and three different microstructures significantly affect the microhardness of the alloy. The formation mechanism of typical microstructure is then clarified by combining the phase diagram and the melt pool convection conditions. Both the microstructure-process relationship and the parameters-microhardness relationship of laser micro-alloyed Ti–6Al–4V+0.3 wt%B alloy are also established.

Influence of TiB2 volume fraction on SiCp/AlSi10Mg composites by LPBF: Microstructure, mechanical, and physical properties

Adding TiB2 particle to SiC particle reinforced Al composite to form TiB2-SiCp/Al composite can increase the tensile properties and lower the thermal expansion coefficient and friction coefficient of the material. The microstructures, mechanical properties, thermal expansion coefficient, and wear behavior of TiB2–SiC particles reinforced AlSi10Mg composites formed by laser powder bed fusion (L-PBF) were investigated in this study. The ultimate tensile strength, thermal expansion coefficient, and the friction coefficient of LPBF-formed 1 vol% TiB2-SiCp/AlSi10Mg composite are 477.6 MPa, 19.91 × 10−6 °C−1, and 0.38, respectively. The results show that the addition of 1 vol% TiB2 weakens the orientation of SiCp/AlSi10Mg composite in the (001) direction. The orientation tends to be random, and the coarse cellular grain with the best orientation in the (001) direction transforms into fine grains in the (111) and (101) directions gradually. This makes the microstructure of the composite be more refined and uniform, eradicating the anisotropy of the temperature gradient, and eliminating the internal stress concentration in the composite. The average grain size of the composite decreases from 3.68 to 1.52 μm. The primary strengthening mechanism of TiB2-SiCp/AlSi10Mg composites is dispersion strengthening. Theoretically, the ultimate tensile strength of the 1 vol% TiB2-SiCp/AlSi10Mg composite is expected to achieve 540.26 MPa.

Processability and characterization of A20X aluminum alloy fabricated by laser powder bed fusion

The processing window for laser powder bed fusion (LPBF) of A20X aluminum alloy was determined to increase the build rate and reduce the fabrication cost for this material. The influence of hatch spacing, laser scan speed, and powder layer thickness on the microstructure and mechanical properties were also systematically investigated. Over a wide processing window (40–115 J/mm3 energy density), near fully dense and crack-free components were achieved. In all cases, the as-built microstructure consisted of an aluminum matrix with TiB2 particles and Al2Cu precipitates, where volume fraction and size of both TiB2 and Al2Cu phases were found to be independent of the LPBF process parameters. A fine equiaxed grain structure with a random crystallographic orientation was observed in the vertical section (XZ-plane) of the as-built samples. This led to an isotropic elastic modulus, ultimate tensile strength, and total elongation. The yield strength, however, was found to be anisotropic, exhibiting a 16 % difference for different orientations. The average grain size decreased 54 % due to increased scan speed and reduced powder layer thickness. This resulted in a remarkable improvement in the alloy micro-hardness value from 108 HV to 124 HV, where the experimental data obeyed the Hall-Petch relationship.

Experimental verification and numerical analysis on plastic deformation and mechanical properties of the in-situ TiB2 homogeneous composites and TiB2/Cu network composites prepared by powder metallurgy

In this paper, three different configurations of composite materials models of TiB2/Cu homogeneous structure, single TiB2/Cu network structure and hybrid reinforced (TiB2p+TiBw)/Cu network structure are established based on their actual microstructure. The models take into account the ductile fracture of the matrix, the brittle fracture of the reinforcing phase and the traction separation behavior of the interface. Influence of mesh size and mass scaling factor on the simulation results are discussed. The validity of the simulation results is verified by the agreement of the experimental tensile stress-strain curve. The effects of TiB2 particle size, volume fraction and hybrid effects of TiB2p+TiBw on plastic deformation and mechanical properties of composites are assessed from the three aspects: interface damage, load-bearing capacity of reinforcement and matrix damage. Compared with the TiB2/Cu homogeneous composites and the single TiB2/Cu network composites, the hybrid reinforced (TiB2p+TiBw)/Cu network composites has better comprehensive mechanical properties, and its tensile strength and elongation are 349 MPa and 10.6 %, respectively. The addition of whiskers can effectively improve the bearing capacity of the hybrid reinforced (TiB2p+TiBw)/Cu network composites, but reduce the elongation of composites.

Preparation and cutting performance of Ti(C7, N3)/TiB2/WC cermet tool material

In this paper, a Ti(C7, N3)/TiB2/WC cermet tool material was prepared by plasma sintering. The components of the tool material and sintering process parameters were optimized through testing mechanical property. The cutting performance of the prepared tool was studied in the cutting experiment of 06Cr19Ni10 austenitic stainless steel. A comparison was made between the prepared tool and the commercial cermet tool SNMN120708. It is shown that when the volume fractions of TiB2 and WC were 20% and 15%, respectively, at the sintering temperature of 1550 °C and with the holding time of 30 min, the prepared tool would possess the flexural strength of 1096.45 Mpa, the hardness of 18.9 Gpa, the fracture toughness of 9.85 Mpa·m1/2 and the optimal cutting speed of 150 m/min. At the cutting speeds of 100 m/min and 150 m/min, the cutting distance of the developed tool was larger than that of SNMN120708. When the cutting speeds were 200 m/min and 250 m/min, the cutting distance of SNMN120708 tool was relatively large. The main wear mechanism of Ti(C7, N3)/TiB2/WC and SNMN120708 tool was adhesive wear, with no trace of abrasive wear.

Transition metal diboride-silicon carbide-boron carbide ceramics with super-high hardness and strength

Three phase boride and carbide ceramics were found to have remarkably high hardness values. Six different compositions were produced by hot pressing ternary mixtures of Group IVB transition metal diborides, SiC, and B4C. Vickers’ hardness at 9.8 N was ~31 GPa for a ceramic containing 70 vol% TiB2, 15 vol% SiC, and 15 vol% B4C, increasing to ~33 GPa for a ceramic containing equal volume fractions of the three constituents. Hardness values for the ceramics containing ZrB2 and HfB2 were ~30% and 20% lower than the corresponding TiB2 containing ceramics, respectively. Hardness values also increased as indentation load decreased due to the indentation size effect. At an indentation load of 0.49 N, the hardness of the previously reported ceramic containing equal volume fractions of TiB2, SiC and B4C was ~54 GPa, the highest of the ceramics in the present study and higher than the hardness values reported for so-called “superhard” ceramics at comparable indentation loads. The previously reported ceramic containing 70 vol% TiB2, 15 vol% SiC, and 15 vol% B4C also displayed the highest flexural strength of ~1.3 GPa and fracture toughness of 5.7 MPa·m1/2, decreasing to ~0.9 GPa and 4.5 MPa·m1/2 for a ceramic containing equal volume fractions of the constituents.

Micromechanics-based simulation of B4C-TiB2 composite fracture under tensile load

Micromechanics modeling was performed to study the effects of thermal residual stress, weak interphases, TiB2 volume fraction and particle size on the mechanical responses and fracture behaviors of B4C-TiB2 composites. Experimentally observed fracture behaviors including micro-cracking and crack deflection were successfully captured. The weak interphases at B4C-TiB2 boundaries and the thermal residual stress induced during cooling by the large CTE mismatch between B4C and TiB2 were identified as two major factors to promote micro-cracking that caused the enhanced progressive failure behavior. Micro-cracking was enhanced with higher TiB2 volume fraction due to higher fraction of weak interphase and material affected by thermal residual stress. Meanwhile, micro-cracking behaviors exhibited limited change with varying TiB2 particle sizes. This modeling study successfully captured the main fracture behaviors and their trends by varying micro-structures of B4C-TiB2 composites and can potentially aid microstructure design of tougher B4C-TiB2 composites in the future.

Effect of in-situ synthesized TiB2 on microstructure and mechanical property of Al/TiB2-SiC interpenetrating phase composites

ABSTRACT Al/TiB2-SiC composites were prepared based on TiB2-SiC porous ceramic preforms. The advantages of this work were characterized by the in-situ synthesized TiB2 in porous ceramic preforms which directly formed interconnected pores as well as TiB2-SiC ceramic skeletons during the one-step ceramic sintering. By controlling in-situ synthesized TiB2 volume fraction, it is possible to tailor TiB2-SiC preform structures so as to determine the structures and mechanical properties of Al/TiB2-SiC composites. The porous ceramic preforms with 20 vol% TiB2 addition achieved the highest porosity, the biggest pore size, but the lowest flexural strength. Al/TiB2-SiC composite with 20 vol% TiB2 addition showed the optimum mechanical properties. The improvement of mechanical properties of Al/TiB2-SiC composites was mainly ascribed to TiB2 additions as well as dense composite structures which were fully infiltrated with Al. This special interpenetrating structural feature and TiB2 addition also constituted an improved toughness through complex crack patterns such as branching, bridging, and deflection.

Influence of Tib2 Volume Fraction on Sicp/Alsi10mg Composites by Lpbf: Microstructure, Mechanical, and Physical Properties

Influence of Tib2 Volume Fraction on Sicp/Alsi10mg Composites by Lpbf: Microstructure, Mechanical, and Physical Properties

Mechanical Properties of Hot-Pressed B<sub>4</sub>C-TiB<sub>2</sub> Composites Synthesized from B<sub>4</sub>C-TiO<sub>2</sub> and B<sub>4</sub>C-TiC

In this study, B4C-TiB2 ceramic composites were manufactured by hot pressing method. The raw materials for the in-situ synthesis of TiB2 were TiO2 and TiC. After being sintered at 1900°C for 60min under a pressure of 30MPa, compact composites samples with a TiB2 volume fraction range from 0 to 11.05% were prepared. The relative density, fracture toughness and flexural strength of different sample were tested. Microstructures on the fracture surface were studied by SEM. The result shows that B4C-TiB2 ceramic composites sintered from B4C-TiC had a better mechanical property than the one sintered from B4C-TiO2. When the content of TiB2 (reacted from TiC) was 11.05vol.%, the strength and toughness of B4C-TiB2 ceramics can reach 598MPa and 6.45MPa·m1/2. The toughening mechanisms of B4C-TiB2 composites include micro-crack toughening and energy consumption by the pulling out process of second phase.

Influences of particle fraction and characteristics on damage tolerance of TiB2-reinforced steel matrix composites

The deformation behaviours of two steel matrix composites (SMCs) strengthened by different volume fractions of the TiB2 ceramic phase were investigated in this work. When the volume fraction of TiB2 was increased from 9 vol% to 13 vol%, the SMC exhibited an unexpected decrease in tensile strength but an improvement in ductility. Thorough experimental investigations based on in-situ and ex-situ microstructural analyses were conducted to reveal the underlying mechanisms. These showed that increasing the volume fraction of TiB2 inevitably led to more primary TiB2 particles with larger sizes and considerable interfacial voids as a result of the hot rolling used in the preparation of the SMC. The primary TiB2 particles were prone to premature fracture owing to higher stress concentrations, and interfacial voids could accelerate the process of microcrack formation and coalescence, leading to a decrease in tensile strength. Such a decrease in the tensile strength of the TiB2-13 vol% SMC was also attributed to the hardness of the ferrite matrix resulting from its low porosity and large secondary phase content. In terms of ductility, the TiB2-13 vol% SMC outperformed the TiB2-9 vol% SMC because the former possessed cleaner ferrite surrounding the primary TiB2 particles.

Combined Effects of TiB Volume Fraction and Orientation on Four-Point Bending Fatigue Properties of TiB-Reinforced Ti–3Al–2.5V Composite

TiB-reinforced Ti–3Al–2.5V, in which the TiB whiskers are oriented parallel to the direction of heat extrusion, was fabricated via powder metallurgy. To investigate the effects of TiB whisker volume fraction on fatigue properties in Ti–3Al–2.5V, four-point bending fatigue tests were conducted on plate-type specimens having TiB whiskers of varying volume fraction and orientation. The fatigue limit and fatigue life of Ti–3Al–2.5V having TiB whiskers that are oriented parallel to the loading direction tended to be increase with increasing TiB volume fraction, whereas the fatigue limit and fatigue life of specimens having TiB whiskers oriented along the short transverse direction did not depend on the TiB volume fraction. The fatigue limit of specimens with TiB whiskers oriented along the long transverse direction tended to decrease with increasing TiB volume fraction, because fatigue cracks were initiated and propagated along the TiB whiskers. Thus, the resistances of fatigue crack initiation and propagation behavior in Ti–3Al–2.5V changed with both the TiB volume fraction and orientation.

In-Situ Synthesis, Microstructure, and Mechanical Properties of TiB2-Reinforced Fe-Cr-Mn-Al Steel Matrix Composites Prepared by Spark Plasma Sintering

In-situ synthesis, microstructure, and mechanical properties of four TiB2-Reinforced Fe-Cr-Mn-Al Steel Matrix Composites have been researched in this work. The microstructure and phases of the prepared specimens have been characterized by using scanning electron microscopy (SEM), X-ray diffraction technique, and transmission electron microscopy (TEM). The sintered specimens consisted of Fe2AlCr, CrFeB-type boride, and TiB2. The mechanical properties, such as hardness and compression strength at room temperature (RT) and at elevated temperatures (600 °C and 800 °C) have been evaluated. The compressive strength and Vickers hardness of the sintered specimens increase with the volume fraction of TiB2 in the matrix, which are all much higher than those of the ex-situ TiB2/Fe-15Cr-20Mn-8Al composites and the reported TiB2/Fe-Cr composites with the same volume fraction of TiB2. The highest Vickers hardness and compressive strength at room temperature are 1213 ± 35 HV and 3500 ± 20 MPa, respectively. As the testing temperature increases to 600 °C, or even 800 °C, these composites still show relatively high compressive strength. Precipitation strengthening of CrFeB and in-situ synthesis of TiB2 as well as nanocrystalline microstructure produced by the combination of mechanical alloying (MA) and spark plasma sintering (SPS) can account for the high Vickers hardness and compressive strength.

Multi-scale reinforcements stimulated dynamic recrystallization and mechanical behavior of as-extruded titanium matrix composites

Different volume fraction of TiB, TiC and La2O3 multiple-reinforced Ti6Al4V composites were fabricated by casting and followed by forging and hot extrusion. The microstructural evolution and mechanical behavior of (TiB+TiC+La2O3)/Ti6Al4V composites during hot extrusion were investigated. The microstructural observations showed that the TiBw and TiCp agglomeration disappeared and distributed more homogeneously in the Ti matrix after hot extrusion. Besides, TiBw exhibited highly preferred alignment along the extrusion direction and TiCp distributed along the same direction. Besides, two kinds of microstructure bands with distinctive spatial distributions of reinforcements were formed after hot extrusion: equiaxial bands embedded with fairly substantial reinforcements and finer basket-weave bands containing few reinforcements, in which the micron-scale TiBw, TiCp and submicron-scale La2O3 particle stimulating nucleation occurred and resulting dynamic recrystallization were the main mechanisms responsible for grain refinement. The tensile tests revealed that hot extrusion significantly increased elongation of (TiB+TiC+La2O3)/Ti6Al4V composites from 2.71% to 13.2% accompanied by slightly decreasing ultimate tensile strength from 954MPa to 903MPa, compared with that of the as-forged composites, which due to a complex process of reinforcements/matrix interaction during extrusion and dynamic recrystallization.

Calculation of Volume Fractions of In Situ TiB and Residual Stress Distributions in Functionally Graded Composite of Ti-TiB-TiB2.

Ti matrix composite with a polylaminate structure was successfully fabricated via spark plasma sintering (SPS) process. A temperature gradient field (TGF) was obtained during the sintering to form functionally graded material (FGM) in a vacuum under 40 MPa for 5 min. The actual volume fractions of TiB in the matrix were calculated based on the X-ray diffraction pattern. The target volume fractions of TiB were 0%, 20%, 40%, 60%, 80% and 100%. The calculated TiB volume fractions were slightly higher than the target volume fractions in layers 2–4 and lower than the target volume fractions in layers 5–6 and the deviations in layers 4 and 5 were less than 5% of the target volume. Based on the elastic axial symmetry model, the residual stress distributions in the Ti matrix composite with a polylaminate structure were simulated, indicating a relatively low thermal residual stress in the FGM.