TiC Reinforcement Research Articles

Effect of cooling rate upon the microstructure and mechanical properties of in-situ TiC reinforced high entropy alloy CoCrFeNi

Three types of in-situ TiC (5 vol%, 10 vol% and 15 vol%) reinforced high entropy alloy CoCrFeNi matrix composites were produced by vacuum induction smelting. The effect of two extreme cooling conditions (i.e., slow cooling in furnace and rapid cooling in copper crucible) upon the microstructure and mechanical properties was examined. In the case of slow cooling in the furnace, TiC was found to form mostly along the grain boundaries for the 5 vol% samples. With the increase of TiC reinforcements, fibrous TiC appeared and extended into the matrix, leading to an increase in hardness. The ultimate tensile strength of the composites shows a marked variation with increasing TiC content; that is, 425.6 MPa (matrix), 372.8 MPa (5 vol%), 550.4 MPa (10 vol%) and 334.3 MPa (15 vol%), while the elongation-to-failure (i.e., ductility) decreases. The fracture pattern was found to transit from the ductile to cleavage fracture, as the TiC content increased. When the samples cooled rapidly in copper crucible, the TiC particles formed both along the grain boundaries and within the grains. With the increase of TiC volume fraction, both the hardness and ultimate tensile strength of the resulting composites improved steadily while the elongation-to-failure declined. Therefore, the fast cooling can be used to drastically improve the strength of in-situ TiC reinforced CoCrFeNi. For example, for the 15 vol% TiC/CoCrFeNi composite cooled in the copper crucible, the hardness and ultimate tensile strength can reach as high as 595 HV and 941.7 MPa, respectively.

Microstructure and Property of In-Situ TiC Reinforced Co-Based Composite Coatings by Laser Cladding

In order to improve the wear resistance of Co-based alloy coatings, in-situ TiC reinforced Co-based composite coatings were prepared on 45 steel surface by laser cladding Co-based alloy, Ti and C powders. The effect of (Ti + C) addition on the microstructure and wear resistance of in-situ TiC reinforced Co-based composite coatings was investigated systematically. The results showed that TiC and Co3Ti phases were detected in the in-situ TiC reinforced Co-based composite coatings, besides γ-Co and Cr23C6. The in-situ TiC reinforced Co-based composite coatings was mainly composed of planar crystals in the binding zone, dendrites in the bottom and equiaxed crystals in the upper. With the increase of (Ti + C) addition, the number of short rod-like dendrites and equiaxed crystals was gradually increased, the microstructure was more fine and uniform. The microhardness of the composite coatings was improved gradually, and the maximum improvement in the microhardness was 35.7%, for 30.0 wt.% (Ti + C) addition. The mass loss of the composite coatings was firstly reduced and then increased, the lowest value was 10.5 mg for 20.0 wt.% (Ti + C) addition, which was 59.7% of that of Co-based alloy coatings, and the wear mechanism of the composite coatings after adding (Ti + C) was the abrasive wear. These results indicated that adding (Ti + C) had a significant influence on the properties of the composite coatings, and were consistent with the calculated results of applied multivariate statistical analysis.

The effect of high TiC particle content on the tensile cracking and corrosion behavior of Al–5Cu matrix composites

The high-TiC particle volume fraction on the mechanical properties and corrosion behavior of the A–5Cu matrix composites were investigated with porosity, hardness, tensile tests, and polarization measurements. The composites reinforced with 18, 27, and 50 vol% TiC particulates were produced successfully by using hot-pressing technique under Ar atmosphere and characterized by scanning electron microscope, electron dispersive spectroscope, and X-ray diffraction. The corrosion susceptibilities of the composites were compared with potentiodynamic scanning technique. It was found that the hardness of the composites increases while the fracture strength decreases with increasing TiC reinforcement content in the matrix. The corrosion susceptibilities of 18 and 27 vol% TiC-reinforced composites are almost the same; the corrosion rate of 50 vol% TiC-reinforced composite was approximately 10 times higher than the composites reinforced with 18 and 27 vol% TiC particles in the 3.5% NaCl. In addition, some preferential corrosion attacks were detected at TiC/matrix interfaces and in TiC clusters during the corrosion process of the composites. Therefore, the porosity content in the composites was almost the same level.

Thermal history analysis and structure-property validation of friction stir welded Al-7079-TiC in-situ metal matrix composites

In the present study, Friction stir welding (FSW) of 6.5 mm thick cast Al-7079-TiC in-situ composite was obtained at 708, 931, 1216 rpm and 40 mm/min respectively. Microstructural characterization of FSWed joints revealed a homogeneous distribution of TiC reinforcements inside the dynamically recrystallized (DRZ) zone. Heat input required for different rotations were analyzed through a coupled study of thermo-mechanical analysis. Heat input was calculated by considering partial sticking and sliding conditions induced between tool and work piece. Transverse and longitudinal tensile test of the weld sections has been conducted. Grain morphology, heat input and TiC particle reinforcement distribution under different tool rotation has been analyzed and has been further correlated with micromechanics approach to validate the mechanical properties of the FSWed specimen. The predicted results have shown a good agreement with the experimental values. Hardness profile has shown a minimum of HAZ among all weld and an average maximum in the DRZ. The weld joint at 931 rpm has exhibited superior mechanical properties as compared to the joints welded at 708 and 1216 rpm respectively.

Nanoindentation Characterization on Microhardness of Micron-Level TiC and TiB Reinforcements in in-situ Synthesized (TiC+TiB)/Ti-6Al-4V Composite

The microhardness of micro-level TiC and TiB reinforcements in in-situ synthesized (TiC+TiB)/Ti-6Al-4V composite were investigated independently by spherical nanoindentation. The morphology of indentation on the matrix, reinforcements and the reinforcement / matrix interfaces were characterized by scanning electron microscope (SEM). The influence of cracks on the load-displacement curves and microhardness were analysed and discussed. The microhardness of TiC and TiB were calculated from the load-displacement curves on reinforcements without cracks. The average microhardness of TiC and TiB in this composite were 24.1 and 19.6 GPa, respectively, which agreed with the values in other composites and coatings. These results verified that the nanoindentation method was a very useful method to characterize the microhardness of micron-level reinforcements in discontinuous metal matrix composite.

Mechanical Behavior of Titanium-Based Layered Structures Fabricated Using Blended Elemental Powder Metallurgy

Mechanical behavior of bilayered structures composed of the layer of Ti-6Al-4 V (wt.%) (Ti-64) alloy and metal matrix composite (MMC) on the base of this alloy reinforced with 5 and 10% (vol.) of either TiB or TiC particles has been studied. Structures were fabricated using blended elemental powder metallurgy and studied by tensile and three-point flexural tests. Mechanical tests were performed on uniform single-layer samples of the alloy as well as individual MMCs. In addition, bilayered structures were also tested in three-point flexural experiment. Posttest fractographic inspections were made using the SEM. The deformation energy was measured based on engineering stress–strain curves obtained on tensile test. The results were compared with the data previously reported on Ti-64 alloy fabricated using cast and wrought technique. The presence of TiB and TiC reinforcement particles in the alloy causes substantial drop in strength and ductility of MMCs as compared to uniform sintered Ti-64 alloy, since those particles provide additional sites for the cracks and pores nucleation and promote the embrittlement of material. However, when MMC layers are used in bilayered structures with Ti-64 alloy layers, the three-point flexural test demonstrates significant increase in flexure stress compared to uniform Ti-64 alloy and uniform structures of MMCs. The suitability of studied structures for antiballistic impact application is discussed.

Effect of red mud and TiC on friction and wear characteristics of Al 7075 metal matrix composites

ABSTRACT Aluminum matrix composites are preferred in various engineering fields such as automobile, marine and aerospace applications owing to their superior properties like high strength to weight ratio, and good wear resistance. The main challenge is to produce MMCs with high strength and wear resistance in a cost-effective manner by utilizing the industrial waste known as red mud is used as reinforcement. In the present study, Al7075/TiC and Al7075/red mud composite samples are fabricated separately after using liquid metallurgy route. During fabrication, the preheated (200-250°C) red mud and TiC reinforcement particles are added at different levels in the ranges from 3–12 wt % in steps of 3 wt% of aluminum. Dry sliding wear and friction characteristics of the fabricated MMCs are studied on a pin on disc wear and friction monitor with and without heat treatment condition. The results have shown improvement for both the specific strength and wear resistance of the developed samples when matched with the base alloy. Further, it is also witnessed that the Al7075/TiC has shown 8 and 19 percentage of improvement in the coefficient of friction and wear rate, respectively when compared with Al7075/red mud composite. Abbreviation: MMCs: Metal Matrix Composites; TiC: Titanium Carbide; SEM: Scanning Electron Microscope; XRD: X-Ray Diffraction

Hardness and Transverse Rupture Strength of TiC-Reinforced SKD11 Steel Matrix Composite

We investigate the effect of heat treatment on the hardness and transverse rupture strength (TRS) in the particulate TiC-reinforced SKD11 steel matrix composites, fabricated by a pressure infiltration casting process. A tempering process softens the composite as-quenched from the austenitization; however the hardness rebounds once the unstable austenite transforms into martensite upon cooling from higher tempering temperature. The fracture strength of steel matrix as well as the fraction and size of reinforcement is likely to affect the TRS of composite. For a given fraction of the TiC reinforcement, higher fracture strength of steel matrix is advantageous to achieve better TRS. Moreover, a refinement of TiC size makes the TRS of the composite more responsive to the change of fracture strength of steel matrix; increasing the fracture strength of steel matrix brings about more improvement of TRS. Thus, smaller TiC reinforcement size provides a better chance to control of TRS of the composite by altering the properties of steel matrix using a heat treatment.

Recent Advances in the Design and Fabrication of Strong and Ductile (Tensile) Titanium Metal Matrix Composites

Titanium metal matrix composites (TiMMCs) offer much improved strength, elastic modulus, and wear resistance at both room and elevated temperatures but often at the expense of tensile ductility, which excludes them from most key engineering applications. Recent advances show that this long‐standing strength‐ductility dilemma can be controlled to a large extent by adopting novel design concepts based on powder metallurgy (PM). These include: 1) reinforcing the Ti matrix with a three‐dimensional (3D) network‐like architecture of TiB whiskers or nanowires; 2) the use of nanostructured carbon precursors (nanotubes, fibers, and graphene) to enable in situ formation of TiC reinforcements; and 3) the exploitation of “ductility‐detrimental” interstitial elements (O, N, H) for strengthening. On a laboratory scale, the fabricated TiMMCs all exhibit an excellent combination of tensile strength and elongation, comparable to, or even better than, solution‐treated and aged (STA) wrought Ti–6Al–4V. The mechanisms behind these novel developments are analyzed. New insights into the design and fabrication of stronger and more ductile (tensile) TiMMCs are offered.

Synthesis of TiC reinforced Ti matrix composites by spark plasma sintering and electric discharge sintering: A comparative assessment of microstructural and mechanical properties

Ti-TiC composite materials were produced by spark plasma sintering (SPS) and electric discharge sintering (EDS) of spherical Ti powders with surface-embedded TiC. Hardness (HIT) and reduced elastic modulus (Er) were estimated using the nanoindentation method with an applied load of 100 mN, and compared with the micro-Vickers hardness value. The microstructure of SPS composite compacts revealed that the TiC particles were uniformly distributed only along the Ti particle boundary. On the other hand, for the EDS composite compacts, the strip-like TiC particles of 1–2.5 µm in size were homogeneously dispersed in the Ti matrix, indicating that the discontinuous and randomly orientated TiC can more efficiently impede the plastic flow of the matrix phase of Ti. The micro-Vickers and nanoindentation hardness for the SPS composite compacts slightly increased with increased TiC content from 0 to 20 wt%, the increments of which were about 67 Hv and 0.7 GPa, respectively. Meanwhile, the EDS composite compacts exhibited significantly higher micro-Vickers and nanoindentation hardness with the increment of 653 Hv and 6.5 GPa, respectively. This result was ascribed to the TiC particles uniformly dispersed across the Ti matrix. Accordingly, the ratio values, such as HIT/Er and HIT3/Er2, were also significantly higher for the EDS composite compacts at all the range of TiC content due to stiffening and hardening effects derived from the TiC reinforcement. Therefore, the better incorporation of the TiC in the Ti matrix significantly improved the hardness and wear properties of the Ti composite reinforced with TiC produced by EDS compared with the SPS process.

Microstructure evolution and its effect on mechanical response of the multi-phase reinforced Ti-based composites by laser powder-bed fusion

The Ti-based composites reinforced by in-situ formed TiB and TiC particles were successfully produced by laser powder-bed fusion (LPBF) additive manufactured technology using a B4C/Ti composite powder mixture, in order to further enhance the mechanical properties of commercially pure titanium (CP-Ti). The effects of applied laser energy density on the microstructure and attendant mechanical properties of the LPBF-processed parts were investigated, and meanwhile, the underlying formation mechanisms of the TiB and TiC particles by LPBF were elucidated. It showed that the whisker-like TiB and near-granular TiC reinforcements were in-situ formed through a laser-induced reaction of Ti-B4C system via a diffusion-nucleation-growth mechanism from the melt. The in-situ reinforcements arranged from dendrite to cellular morphology were primarily determined by the thermal convections that transformed from dendrite to annular patterns as a result of the great elevation of temperature gradient between molten Ti liquid and heated B4C particles as an increase in the applied laser energy density. The tensile tests revealed that the LPBF-ed Ti-based composites possessed an enhanced tensile strength from 893 ± 5 MPa to 1211 ± 8 MPa and a slightly reduced elongation from 18.1% to 16.8% with the transition of typically fracture morphologies from elongated dimples to equiaxed-ultrafine dimples, respectively, attributed to the combined grain refinement and microstructure strengthening effects.

Effect of Carbon Content on Microstructure and Properties of TiC Reinforcement Composite Coatings by Laser Cladding

Effect of Carbon Content on Microstructure and Properties of TiC Reinforcement Composite Coatings by Laser Cladding

Effect of Fine TiC Particle Reinforcement on the Dry Sliding Wear Behavior of In Situ Synthesized ZA27 Alloy

The in situ method of making zinc-aluminum composites wherein TiC has been introduced has been investigated in the present paper for its microstructural, physical, and dry sliding wear behavior and compared with the base alloy. In the present study, ZA-27 alloy reinforced with 5 and 10 vol % TiC was taken into consideration. The results indicate that the wear rate and coefficient of friction of composites were lower than that of base alloy. The material loss in terms of both wear volume loss and wear rate increases with increase in load and sliding distance, respectively, while coefficient of friction follows a reverse trend with increase in load. Better performance was obtained for 5% TiC reinforcement than with 10% probably due to agglomeration of particles resulting in nonuniform dispersion. Worn surfaces were analyzed by scanning electron microscopy (SEM) analysis.

An investigation into fabrication and characterization of direct reaction synthesized Al-7079-TiC in situ metal matrix composites

The present study was attempted to highlight a novel direct reaction synthesis in which traditional casting plus rapid solidification techniques were implemented to produce Al-7079-TiC in situ composites with homogenous microstructure and improved dispersion strengthening by the reinforcing phases. Casted samples were effectively characterized by scanning electron microscopy followed by energy dispersive spectroscopy and X-ray diffraction. Ingot metallurgy showed a homogenous distribution of TiC particles inside the grain. This particle behavior acted as an excellent nucleation sites for the Al dendrites to grow unvaryingly. TiC reinforcements have semi coherent relationship with α-Al matrix. It was observed that eutectic boundary includes the second phases based on η (MgZn2) and Mg(Zn, Cu, Al)2. Almost 90% of the in situ reinforced TiC were homogenously distributed along the center of the grain. Thermal history conditions have shown an exothermic behavior during casting. Experimental results revealed the evolution of TiC particles in super-heated melt region, i.e. dissolution of titanium continued by reaction of titanium with diffused carbon in the Al matrix to form TiC particles. Further they acted as nucleation sites for the α-Al dendrites to grow homogenously. This study presents optimum process temperature for the Al-TiC in situ synthesis.

INVESTIGATION OF MECHANICAL AND CORROSION PROPERTIES OF AA2024–B4C–TiC HYBRID METAL MATRIX COMPOSITES

Metal matrix composites are widely applied in the automotive and aircraft structural components. This work investigates the influence of mechanical and corrosion properties hybrid aluminium 2024 metal matrix composites having 5%, 10%, 15% and 20% of TiC and B4C (equal amount) reinforcement compositions. The increase in volume fraction of B4C and TiC particle in matrix alloy increases the hardness, yield strength, ultimate strength and decreases the ductility of the composite. SEM images show microstructure of the composites with particles having a different volume percentage of reinforcement. The uniform distribution of B4C and TiC particles is most predominant in composite fabrication and the reinforcement particle additions have proved improved corrosion resistance in AA2024–B4C–TiC MMCs.

Comparative investigation on microstructures and mechanical properties of (TiB + TiC)/Ti-6Al-4V composites from Ti-B4C-C and Ti-TiB2-TiC systems

Two percentages of TiB + TiC reinforced Ti-6Al-4V composites from Ti-B4C-C and Ti-TiB2-TiC systems were fabricated by reactive hot-pressed sintering. Their microstructures and mechanical properties involving elastic modulus, Vickers hardness, bending strength and wear property were investigated comparatively. The experimental results show that needle-like TiB whiskers and near-equiaxed TiC particles are evenly distributed in the Ti-6Al-4V matrix. The mechanical properties of the (TiB + TiC)/Ti-6Al-4V composites are closely related with the nominal composition and synthesis system of TiB + TiC reinforcement and the microstructures of composites. With increasing the nominal volume fraction of reinforcement, both elastic modulus and Vickers hardness increase more or less and the bending strength decreases in varying degrees. A certain increase of pores in the composites with the sintering temperature increasing to 1300 °C can markedly affect the bending strength. Moreover, no matter what the sintering temperature and nominal volume fraction of reinforcement, the elastic modulus and Vickers hardness of composites from the Ti-TiB2-TiC system are higher than those from the Ti-B4C-C system. Similarly, the composites from the Ti-B4C-C system present better abrasion resistance than those from the Ti-TiB2-TiC system due to the difference of interfacial bonding between the TiC particles and Ti-6Al-4V matrix in the two kinds of composites.

TiC – Based local composite reinforcement obtained in situ in ductile iron based castings with use of rode preform

Highexothermic type of reaction synthesis of TiC prevents obtaining stable dimensionally composite reinforcement in castings based on Fe alloys. The article presents a new method of in situ manufacturing of local composite reinforcement in ductile iron casting. The synthesis of TiC was performed by placing the substrates of reaction of its formation in a steel tube. A preform rod containing the substrates was placed in mould cavity and then poured the liquid casting alloy prevents in the same time the fragmentation of composite reinforcement during the synthesis reaction. As a result, composite casting with TiC reinforcement was obtained. The preform placed in a mould cavity showed thermal stability and was not melted. The presence of ceramic phase in a form of TiC caused the increase of hardness by more than 300%, when compared to matrix alloy. Workout method is a good candidate to obtain structural reinforcements in castings on Fe-based alloy.

Study of W-Co ODS coating on stainless steels by mechanical alloying

Tungsten-based coatings have attracted considerable interest in recent years for industrial applications because of superior wear resistance. In this study, the W-Co oxide dispersion strengthened (ODS) coating on stainless steels by mechanical alloying (MA) has been investigated. The different reinforced particles (Y2O3, TiC) have been introduced to the W-Co coating layer as dispersion strengthening during mechanical alloying. The results showed that the formation of the (W,Co)C, Co7W6 and Co3W phases was generated after a long milling duration. The use of Y2O3 dispersed particles in the coating layer demonstrated homogenous distribution of microstructure and an increase of mechanical properties. However, the coating with TiC reinforcement has a significant change in distribution of the microstructure and composition and formed voids or micro-cracks, which decrease densification and hardness of the coating materials. The W-Co ODS coating by mechanical alloying is one of the most promising coating methods for enhanced wear resistance on stainless steels.

In situ synthesized TiC/Mo-based composites via laser powder bed fusion

A strategy utilizing carbon nanotubes (CNTs) was put forward to synthesize in situ TiC/Mo-based composites via laser powder bed fusion (laser PBF). The functionalized CNTs were dispersed with MoTiAl powders under electrostatic attraction by heteroagglomeration. During laser PBF, individual CNTs reacted with Ti elements and were completely transformed into monocrystalline TiC. Those TiC reinforcements were homogeneously dispersed and intimately contacted the matrix, giving rise to the morphological evolution of a MoTiAl matrix from the nearly columnar to fine equiaxed grains as well as improved mechanical performance. Our finding offers significant guidance for designing and producing advanced Mo-based composites in the application of heat-resistant materials.

Optimization of EDM Parameters for Al – TiC Composites Prepared through Powder Metallurgy Route

This work focuses on the behavior of Aluminum (AP50) reinforced with Titanium Carbide Metal Matrix Composite (MMC) during machining in Electrical Discharge Machining (EDM) process. While machining a MMC through conventional machining process poor surface finish and lower metal removal rate are experienced. Hence the nonconventional machining technique EDM is the best alternate to machine intricate shape in MMC. The material used in this study is Aluminum (AP 50) with 3 proportions of TiC (i.e., 2.5%, 5% and 7.5%). The machining is performed by varying the Pulse On time, Pulse Off time and Peak Current while other parameters such as Dielectric flushing pressure, Electrode feed rate and Applied voltage are kept unchanged. The parameter optimization is performed using Taguchi techniques. It is found that increase in Metal removal rate and reduction in surface roughness is achieved with the 2.5% percentage TiC reinforcement. It is also found that the metal removal rates as well as surface roughness are more influenced by the parameters Peak Current and Pulse on Time. DOI: http://dx.doi.org/10.5755/j01.mech.24.1.18951