Effect Of TiB2 Addition Research Articles

Refinement of cast microstructure of A517 steel by addition of TiB2

The effect of TiB2 addition on microstructure refinement of the as-cast and reheated A517 steel has been investigated. 0.1 wt.% TiB2 addition resulted in a reduction in equiaxed γ grain size from 990 ± 183 to 116 ± 35 μm and an increase in the volume fraction of equiaxed γ grain region from 5% to 67% in the as-cast A517 steel ingots. Microstructure analysis identified TiN particles rather than TiB2. This is attributed to the low thermodynamic stability of TiB2, leading to its decomposition into free Ti and B elements at an elevated temperature. Then, chemical reaction between the free Ti and residual nitrogen in the liquid resulted in the formation of TiN. Hence, it is considered that TiN acted as heterogeneous nucleation sites for the δ-ferrite. This initiated the refinement and columnar to equiaxed transition of δ-dendrites. As a result, the subsequently formed γ grains were correspondingly refined. Such microstructure refinement led to improvement of the yield strength and ultimate tensile strength of the as-cast A517 steel. However, the reheating of the as-cast A517 steel resulted in a marginal microstructure refinement in the samples with low TiB2 addition. This is attributed to the limited pinning effect of the coarse TiN particles formed during casting process. Consequently, the tensile properties of the reheated A517 steel remained unaffected by the TiB2 addition.

Effect of TiB2 Addition on the Microstructure and Mechanical Properties of Laser-Directed Energy Deposition TiAl Alloy

The microstructure characteristics of TiAl alloy prepared by laser-directed energy deposition (L-DED) are coarse columnar grains parallel to the building direction, which results in serious mechanical properties and anisotropy and limits its application. In the present study, TiB2 can be used as an effective grain refiner due to the extremely high Q value (growth inhibition factor; the larger the Q value of an alloying element, the stronger its grain refinement effect.) of B. With TiB2 addition, TiAl alloys prepared by laser-directed energy deposition with the microstructure of full equiaxed grains were obtained, and the grain size was significantly reduced by about 30% with 0.45 wt.% TiB2. This value has been further increased to 45% when adding 0.9 wt.% TiB2. Moreover, the γm phase was nearly eliminated and the width of (α2 + γ) lamellar was significantly decreased, which has positive effects on mechanical properties. Meanwhile, TiB2 precipitates uniformly distribute in the matrix, as a reinforced particle to increase the hardness and compressive strength of the alloys. The microhardness of the TiAl alloy increased with the increasing content of TiB2. The addition of TiB2 improved the room and high-temperature compressive properties of TiAl alloy while slightly increasing its ductility. These findings have important guiding significance for expanding the application of TiAl alloys.

Effect of TiB2 Addition on Microstructure and Mechanical Properties of AA8009 Alloy Fabricated by Laser Additive Manufacturing

Effect of TiB2 Addition on Microstructure and Mechanical Properties of AA8009 Alloy Fabricated by Laser Additive Manufacturing

Effect of TiB2 addition on the mechanical and biological response of spark plasma sintered Ti6Al7Nb matrix composites

In situ fabrication of TiB whiskers (TiBw) reinforced Ti-matrix composites (TMCs) was carried out with the addition of TiB2 particles in Ti6Al7Nb matrix using low energy ball milling and subsequent consolidation via Spark Plasma Sintering (SPS). The ball mixing of 0.5 %, 1.5 %, and 3 % TiB2 resulted in its distribution ratio (RD) of 1.05, 3.2, and 6.5, respectively. The in situ TiBw formations as a reaction between the Ti6Al7Nb matrix and TiB2 particles resulted during sintering. This TiBw inclusion in different regions caused the retardation of grains from growing and resulted in grain refinement. The presence of a stiff TiBw phase in combination with grain refinement was ascribed to the increased hardness and higher strength in the fabricated composites. Maximum hardness (~ 496 Hv) and strength (~ 2233 MPa) was achieved in the 3 % TiB2 containing composites among all. The biological response showed better cell adhesion and proliferation without any toxic effect on all fabricated samples when compared to the wrought Ti6Al7Nb. The enhanced cell proliferation on the TiBw composites than the pure alloy demonstrates them as promising materials for biomedical applications.

Effect of TiB2 addition on microstructure and mechanical properties of a hypereutectic high chromium cast iron

Effect of TiB2 addition on microstructure and mechanical properties of a hypereutectic high chromium cast iron

Mechanical and ballistic properties of graphene platelets reinforced B4C ceramics: Effect of TiB2 addition

This study reports the experimental investigations on the mechanical properties and ballistic performance of the dual-phase (GPLs-B4C) and trio-phase (GPLs-B4C–TiB2) ceramic composites. Both graphene platelets (GPLs) reinforced ceramic composites were fabricated by the hot-pressing method. The influences of the sintering additive, TiB2, on the hardness, flexural strength, fracture toughness, static and dynamic compressive strength, and ballistic performance of the GPLs-B4C composite were studied. Results ascertained the beneficial effect of adding the TiB2 as a sintering phase for the GPLs-B4C ceramic composite. The hardness, flexural strength, fracture toughness, dynamic strength (at 900 s−1) and ballistic efficiency of the GPLs-B4C–TiB2 composite reached 27.98 ± 0.69 GPa, 555.48 ± 7.50 MPa, 4.80 ± 0.31 MPa⋅m1/2, 4.99 GPa and 6.72, which are 19.7%, 24.1%, 19.7%, 31.6% and 18.1%, respectively, higher than that without the TiB2 addition. Experimental results showed that both GPLs-B4C and GPLs-B4C–TiB2 are strong rate-dependent composites with nonlinearities in their constitutive behaviours under quasi-static and dynamic compressive loadings. In-depth SEM investigation revealed that the enhanced performances under dynamic compression and impact loading are due to the combination of failure mechanisms of the GPLs-B4C–TiB2 ceramic composite – it is a mixed inter/trans-granular fracture mode – and the toughening mechanisms offered by the reinforcing phase (GPLs). The anchoring effect of GPLs was identified, which attributes to its toughening mechanisms for the current composites through crack deflection and crack bridging. This work may be served as an experimental basis for the design and application of GPLs-B4C–TiB2 composite for ballistic protection.

Effect of TiB2 addition on microstructure and fluidity of cast TiAl alloy

Effects of TiB2 addition on Microstructure and Fluidity of Ti–48Al–2Cr–2Nb + xTiB2 (x = 0.18, 0.36, 0.54, 0.72, 0.9, 1.8 wt%) alloys fabricated by vacuum non-consumable tungsten arc melting were investigated. Results showed that with adequate TiB2 addition (0.72% TiB2 and more), the as-cast microstructure transformed from coarse columnar grains to fine equiaxed grains, and the grain size was reduced from 800 μm to 200 μm. The morphology of borides transformed from flake to block and needlelike, resulted from the dissolution and re-precipitation of original TiB2 powders. The fluidity of TiAl alloy was improved by the addition of TiB2, and the T4822–0.72TiB2 alloy showed the largest filling length of 266.5 mm, 17.4% higher than that of the matrix alloy. The enhancement of fluidity and the cessation mechanism of melt flow for the TiB2-containing TiAl alloy were analyzed and discussed in light of the microstructure evolution, borides and solidification characterization.

Dry Sliding Friction and Wear Behaviour of AA6082-TiB2 in Situ Composites

In this study a composite with AA6082 as the matrix and TiB2 as the reinforcement has been fabricated by in situ method. The effect of TiB2 addition on the mechanical and tribological behaviour has been investigated. The purpose of the study is to improve the friction and wear properties of AA6082 so as to widen the engineering applications of the alloy. The reinforcement varied as (0, 3, 6, 9 wt%). The mechanical characteristics such as hardness and density improved with the addition of the reinforcement particles. The microhardness also shows slight increase in its value with increase in reaction time. The microstructural examination depicted grain refinement of the cast composites with increase in reinforcement. The wear resistance also increases with the addition of the reinforcement. The coefficient of friction exhibited an increasing trend and thereafter it decreased with increasing reinforcement at lower load. However, at higher load, an increase in the coefficient of friction is observed with an increase in reinforcement. SEM and EDS analysis revealed distinct wear mechanisms for different composites and different loads. The present study reveals that with addition of hard TiB2 particles the mechanical and tribological of AA6082 are improved. The results suggest that the developed composite material could be a potential material for various engineering applications.

Effect of TiB2 addition on the elevated temperature tribological behavior of spark plasma sintered Ti matrix composite

The study aims at the investigation of the high temperature tribological behavior for in situ synthesized Ti–TiB composite and reports thorough characterization of worn surfaces to understand the operative wear mechanisms to clarify the controversial role of tribo-oxide formation in Ti alloys. Therefore monolithic CpTi and CpTi+9.6 wt% TiB2 composite specimens were fabricated by spark plasma sintering. Microstructural and phase analyses verified the in situ formation of TiB whiskers in the composite specimens and an enhancement in hardness. The dry sliding wear behavior of composites was better than CpTi, across all testing temperatures, thanks to better hardness and the formation of adherent and thicker tribo-oxide layer.

Effect of TiB2 addition on wear behavior of (AlCrFeMnV)90Bi10 high entropy alloy composite

Abstract The present investigation reports development of a novel self-lubricating high entropy alloy composite; AlCrFeMnV BCC alloy as a matrix along with Bi and TiB2 as a solid lubricants, synthesized using spark plasma sintering. In particular, synergistic effect of soft Bi and hard TiB2 on tribological behavior of the HEA composite has been correlated with microstructure. TiB2 addition leads to 85% decrease in wear rate compared to base alloy. Exceptional decrease in wear rate is due to high hardness of TiB2 and uniformly dispersed Bi particles, which undergo softening and melting during sliding acting as a lubricating film between the sliding bodies. Computational modeling of contact stress and temperature during wear was performed to study surface and subsurface deformation and temperature rise during wear.

Effect of TiB2 addition on the microstructure and wear resistance of Ti-6Al-4V alloy fabricated through direct metal laser sintering (DMLS)

Recent trend in additive manufacturing of Ti-6Al-4V alloy is to alter the microstructure by changing process parameters or by the addition of alloying elements to achieve the required performance. In the present investigation direct metal laser sintering (DMLS) processed Ti-6Al-4V alloy with addition of varying amount of TiB2 has been successfully fabricated. Effect of addition of TiB2 on microstructure, hardness and wear performance was studied using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), electron back scattered diffraction (EBSD), Vickers micro-hardness and pin-on-disk tribometer respectively. With the increase in addition of TiB2, the microstructure changed from martensite (α′) lath to refined bimodal structure. Consequently, hardness and wear performance showed dramatic improvement. An elementary hypothesis is proposed for the formation of bimodal structure instead of the martensite structure which is generally observed in DMLS processed Ti-6Al-4V.

Effect of TiB<sub>2</sub> on Pressureless Sintering and Hot Pressing of ZrB<sub>2</sub>

Zirconium diboride (ZrB2) is a material of particular interest because of the excellent and unique property combination of high melting point and high electrical and thermal conductivity. In this work, the effect of TiB2 addition on pressureless sintering and hot pressing sintering of ZrB2 was investigated. Four compositions were prepared with 0, 5, 10 and 20 wt% of TiB2. First, ZrB2 and TiB2 powders were milled by planetary mill with SiC spheres at for 4 h and then they were wet mixed. Compacted samples were pressureless sintered at 2150 oC/1h and hot pressed at 1850 °C/30min with 20 MPa, both in Ar atmosphere. The added TiB2 completely dissolved into the structure and formed a solid solution with ZrB2. Addition of TiB2 in ZrB2 ceramic improved densification and hardness for both sintering process, but hot pressed samples exhibited better results.

Tribo-Mechanical Properties of HVOF Deposited Fe3Al Coatings Reinforced with TiB2 Particles for Wear-Resistant Applications

This study reveals the effect of TiB₂ particles on the mechanical and tribological properties of Fe₃Al-TiB₂ composite coatings against an alumina counterpart. The feedstock was produced by milling Fe₃Al and TiB₂ powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB₂ addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s-1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe₃Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB₂ content in the Fe₃Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB₂ particles but were less dependent on the applied load.

A Comparison between B<sub>4</sub>C-TiB<sub>2</sub>-Al Composite and B<sub>4</sub>C-Al Composite on Microstructure and Mechanical Properties

B4C-Al and B4C-TiB2-Al composites were fabricated by infiltrating aluminum into porous B4C and B4C-TiB2preforms in vacuum. The effect of TiB2addition on the microstucture and mechanical properties of the B4C-Al composites were investigated. The flexural strength and the fracture toughness of composite improved greatly as the result of TiB2addition. The TiB2addition inhibited the reaction between B4C and Al. The infiltrated aluminum addition was the leading reason for the fracture toughness improvement of the composites. Inter/transgranular fracture mode with many tear ridges and dimples was showing in the fracture surface of the B4C-TiB2-Al composite. The relationships between the microstructures and the mechanical properties of the B4C-TiB2-Al composites were discussed.

Reduction in densification temperature by TiB2 addition during sintering of oxides

Several oxide powders (SrTiO3, BaTiO3 and Y2O3) were mixed with TiB2 powder and then sintered by the SPS process. The effects of TiB2 addition on the densification behaviours of these oxides during SPS were investigated and its mechanisms were discussed. The TiB2 addition was found to be quite effective for reducing the densification temperature of these oxides during sintering. In the case of the SrTiO3, after sintering, the sample was composed of SrTiO3 and TiB2 only, indicating that reactive sintering and/or liquid phase sintering did not occur. Even when sintered by the conventional hot pressing, it was found that TiB2 addition was also quite effective for reduction in densification temperature as well as when sintered by SPS, suggesting that the effect of TiB2 addition is available for the conventional heating process. These experimental results show the possibility of TiB2 as a sintering agent for low temperature densification of oxides.

Pressureless Sintering of TiB2-B4C Ceramic Matrix Composite

The effect of TiB2 addition on sinterability and mechanical properties of B4C material was investigated. It was found that addition of TiB2 aids the sintering process and permits pressureless sintering at temperatures between 2050 and 2150 °C. This also alleviates grain growth during sintering. The relative density reaches 98.5% of the theoretical density by increasing the percentage of TiB2 in the composition. The mechanical properties such as hardness, fracture toughness, and bending strength were improved remarkably by addition of TiB2.

Mechanical properties and tribology of Si3N4–TiB2 ceramic composites produced by hot pressing and hot isostatic pressing

Ceramic matrix composites containing TiB2 as a particulate phase have been produced by hot pressing and hot isostatic pressing. The problems of the reactivity of TiB2 with the Si3N4 matrix and with the sintering environment have been successfully addressed. A novel dual atmosphere sintering profile combined with low temperature hot pressing has been used to successfully produce fully dense materials. The effect of TiB2 addition on mechanical properties has been investigated and the tribological behaviour of optimised compositions has been examined using a ball-on-disc apparatus. Wear coefficients and friction coefficients for Si3N4–TiB2 composites have been measured and compared to monolithic Si3N4 materials. Composites containing TiB2 show significant improvements in hardness, fracture toughness and wear whilst also exhibiting electrical conductivity.

Production and EDM of Si3N4–TiB2ceramic composites

Ceramic matrix composites containing TiB2 as a particulate phase have been produced by hot pressing. The problems of the reactivity of TiB2 with the Si3 N4 matrix and with the sintering environment have been successfully addressed. A novel dual atmosphere sintering profile combined with low temperature hot pressing has been used to successfully produce fully dense materials. The effect of TiB2 addition on mechanical properties has been investigated. Composites containing TiB2 show significant improvements in hardness and fracture toughness. The addition of TiB2 at a level of 40 vol.-% raises the conductivity of the composite to a level where electro-discharge machining (EDM) is possible. A comprehensive study of the application of EDM has been carried out and the optimum machining conditions have been identified. Under these conditions Si3 N4–TiB2 composites have been shaped with relative ease and proved to be ‘robust’ materials under EDM.