Effect Of Titanium Addition Research Articles

Effect of Titanium Addition on As Cast Structure and Macrosegregation of High‐Carbon High‐Chromium Steel

AbstractIn casting heavy ingots of high‐chromium high‐carbon cold work steels, macrosegregation develops in the center of the ingot, causing difficulties during subsequent hot working. Heat transfer and solidification of an industrial scale high‐carbon high‐chromium steel ingot was simulated and thereafter a laboratory scale representative ingot was designed to model the solidification of the industrial scale ingot. Titanium in the range of 0.3–1% was added to the high‐chromium high‐carbon (12%Cr–2%C) steel during melting process. Microstructures, macrosegregation and phase formations were studied using optical microscopy, scanning electron microscopy, energy dispersive X‐ray spectrometry, wave dispersive X‐ray spectrometry, optical emission spectroscopy, and X‐ray diffraction. Addition of 0.3% titanium was sufficient to diminish the macrosegregation; however it did not have a significant effect on the grain size. Addition of 0.7 and 1% titanium had a substantial effect on grain size in the longitudinal direction and refined the primary carbides structure. The formation of small TiC carbides that precipitated before solidification of liquid iron acted as nuclei for primary pro‐eutectic austenite grains.

Effect of titanium addition on structure and properties of the as-cast high Cr–Mo white iron

Abstract This work analyses the wear behaviour and impact toughness of high Cr –Mo white irons alloyed with titanium as related to their microstructure and solidification path. Five alloys were used with different percentages of titanium (0, 0.47, 0.932, 1.31 and 1.78 %). Such additions of titanium resulted in precipitation of small hard TiC particles in the austenitic matrix. These particles were well distributed in the matrix with Ti-additions up to 1.31% and then started to agglomerate with 1.78%Ti. Hardness increased dramatically with increasing amount of titanium addition. The wear behaviour was investigated for each alloy in the as-cast condition using the pin-on-ring configuration for 30 min against a ring made of SiC that rotated at a constant speed of 65 rpm. The wear test was performed under a load range of 30–180 N. The results are discussed in terms of microstructure and the minimum wear rate was obtained for the white cast iron alloyed with 1.31% titanium. The optimum tensile strength, impact toughness and wear resistance were also observed for the iron alloyed with 1.31% titanium. However, these properties started to deteriorate with further increase in titanium addition due to the clustering effect of titanium carbide particles in the austenitic matrix. Therefore, the optimum wear resistance and impact toughness of white cast iron under investigation (16% Cr-1.3% Mo-2.3% Ni) can be achieved by adding 1.31% titanium.

Effect of Titanium Addition on Behavior of Medium Carbon Steel

This work aims at investigating the influence of titanium addition on behavior of medium carbon steel. Three types of medium carbon steel with different titanium content and one reference steel titanium free were produced in 100 kg induction furnace. Titanium addition was increased up to 0.230%. The produced steels were forged at start temperature 1150°C. Forging process was finished at temperatures 900°C, 975°C, and 1050°C. Microstructure examination and hardness measurement were carried out for forged steels. Mechanical properties and impact measurements were carried out for quenched tempered steels. Ti addition was found to have significant influence on refinement of grains and increase of ferrite/pearlite ratio. It was also, observed that grain size decreases as finishing temperature of forging process decreases. Both Ti addition and lowering finishing forging temperature have positive effect on hardness. In addition, results indicated that addition of titanium has significant effect on the mechanical properties and toughness.

CuZrAlTi Bulk Metallic Glass with Enhanced Glass‐Forming Ability, Mechanical Properties, Corrosion Resistance and Biocompatibility

AbstractThe effect of titanium addition on the glass forming ability (GFA), plasticity, corrosion resistance and biocompatibility of CuZrAl alloy are evaluated by XRD, DSC, compression tests, corrosion, and cytotoxicity tests. The GFA of Cu45Zr48Al7 amorphous alloy is greatly improved by titanium addition, as evidenced by the increase of critical size from less than 8 mm for Cu45Zr48Al7 alloy to 10 mm for Cu45Zr46.5Al7Ti1.5 alloy when the samples are prepared by copper mold casting. Cu45Zr46.5Al7Ti1.5 alloy shows enhanced plastic strain up to 10%, good corrosion resistance and biocompatibility in comparison to Cu45Zr48Al7 alloy.

The Effect of Titanium Addition on Microstructure and Properties of Laves Phase Cr<sub>2</sub>Nb Alloy Synthesized by Hot Pressing

The composite materials with a nominal composition of Cr2Nb-24wt.%Ti were fabricated by mechanical alloying followed by hot pressing. The microstructures and properties were investigated on the composites contained with Laves phase prepared through 20 hours mechanical alloying of chromium, niobium and titanium elemental powders and hot pressing at 1250°C for half an hour. The results indicate that the near full-dense Laves phase Cr2(Nb,Ti) based alloy with homogeneous composition and microstructure is obtained by mechanical alloying and hot pressing techniques. The dispersed soft second phase Nb solid solutions with the fine grain size less than 1μm are distributed uniformly on the matrix. The sample has a relative density of 99%, fracture toughness of 5.32MPa•m1/2 and compress strength of 2080MPa. Due to the effect of fine-grain and alloying addition, the toughening of the Cr2(Nb,Ti) based alloy has been fully realized.

Effect of titanium on second phase precipitation behavior in 9–12Cr ferritic/martensitic heat resistant steels

Effect of titanium addition from 0.003 to 0.140 wt.% on precipitation behavior of MX-type phase in 9–12Cr ferritic/martensitic heat resistant steels was studied. The results show that large titanium-containing MX particles with about 1μm form from liquid metal during the solidification process in high titanium steel. After normalizing at 1100 °C for 1 h, cooled in air and tempering at 750 °C for 1 h, nanometer-sized MX precipitates distribute densely near martensitic lath boundaries in the high titanium steel. Two kinds of nanometer-sized MX precipitates distribute densely and homogeneously in the matrix within lath in low titanium and ultra low carbon steels after the same heat treatment. The relatively larger nanosized MX precipitates have a size more than 30 nm and contain titanium. The number density of the relatively larger nanosized MX precipitates increases with the increasing of titanium content. The relatively smaller nanosized MX precipitates are about 10 nm in size and have two kinds of different shapes: one is cubic and contains titanium, and another rectangular without titanium.

Effect of titanium addition on the magnetic property of Nd 2Fe 14B/α-Fe nanocomposite alloys

Rapidly solidified nanocrystalline a-Fe/Nd 2Fe 14B alloys with enhanced coercivity were obtained by melt spinning. The effects of Ti addition on the microstructure and magnetic properties of the nanocomposite a-Fe/Nd 2Fe 14B alloys were investigated by X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometer. The analysis of XRD showed that V a-Fe estimated to be about 35.3% in the Ti-free a-Fe/Nd 2Fe 14B nanocomposites decreased down to 26.5% as the addition of was 5 at.% Ti. Accordingly, adding Ti resulted in relevant improvements of magnetic properties, especially of the coercivity H c from 595 kA/m up to 1006 kA/m. The dependence of M irrev( H)/2 M r on the reverse field H indicated that nucleation was the dominating mechanism for the magnetization reversal in these nanocomposites. The analysis of the temperature dependence of the demagnetization curve in the a-Fe/Nd 2Fe 14B nanocomposite magnets indicated that a reduction of a ex could play a leading role in an increase in the coercivity of Ti-doped sample.

Effects of titanium addition on mechanical and corrosion behaviours of AZ91 magnesium alloy

The mechanical properties and corrosion behaviour of AZ91 magnesium alloy containing 0.2–0.5 wt.% Ti were investigated in this study. Results demonstrate that the enhancement of the ultimate tensile strength by 18% and yield strength by 47% can be achieved by Ti addition. The corrosion behaviour was evaluated by immersion tests and potentiodynamic polarisation measurements in 3.5% NaCl solution. The results from the immersion tests and potentiodynamic polarisation measurements showed that the corrosion resistance of AZ91 alloy increased progressively with the increase of the Ti content of the alloy. Compared to AZ91 alloy, 0.5Ti addition increased the corrosion resistance by up to 45 fold. The mechanism of property enhancement is ascribed to both the suppression of partially divorced β-Mg 17Al 12 eutectics and an increased Al content in α-Mg solid solution by Ti addition in AZ91 alloy.

TiAlSi intermetallic formation and its impact on the casting processing in Al–Si alloys

The effect of titanium additions on the formation of primary TiAlSi intermetallics and resulted cast microstructure in Al–Si alloys has been studied. The precipitation temperature, growth kinetic and morphology of TiAlSi intermetallics as well as the solubility limit of Ti in Al–Si alloys were experimentally evaluated. The impact of primary TiAlSi intermetallic particles on the casting process related problems was investigated on the large scale of industrial production. The influence of Ti in the occurrence of feeding blockage and wormhole defect during ingot casting was described. The perspectives of Ti addition in Al–Si cast alloys were discussed. It is proposed that the Ti level in the most Al–Si cast alloys should be controlled within 0.10 wt.%.

Lean neodymium Nd–Fe–B magnets containing minor addition of titanium

AbstractThe effect of titanium addition on the structure and magnetic properties was studied for the nanocomposite Nd7Fe79–xB14Tix and Nd8Fe78–xB14Tix systems. The alloys were rapidly solidified by melt‐spinning with the roll speed 20 m/s. The overquenched, amorphous ribbons were subsequently crystallization annealed for 20 min at 953–973 K. It was found that the addition of 2 and 4 at% of Ti leads to a substantial increase of the coercivity and maximum energy product of the nanocomposite magnets while maintaining the remanence unchanged. The highest properties were obtained for the alloys containing 4 at% of Ti. The maximum energy product of 143 kJ/m3 was achieved for the Nd8Fe74B14Ti4 alloy. The TEM studies showed substantial differences in the morphology of the alloys. The ternary alloys contain grains of various sizes of approximately 300 nm. The alloys containing 4 at% of Ti exhibit more homogeneous structure with the crystal sizes up to 30 and 50 nm for the Nd8Fe74B14Ti4 and Nd7Fe75B14Ti4 alloys, respectively. More detailed information on the phase constitution was obtained from the Mössbauer spectroscopy. Comparison of the Ti‐free and 4 at% Ti alloys revealed that the amount of the hard magnetic Nd2Fe14B phase decreases from 84.53 to 69.88% for the Nd7Fe79–xB14Tix system and increased from 66.60 to 82.48% for Nd8Fe78–xB14Tix system.

Abstract: P835 CHARACTERIZATION OF THE LOW DENSITY LIPOPROTEIN RECEPTOR (LDLR) GENE MUTATION IN ALBANIA

Rapidly solidified nanocomposite Nd9Fe77−xB14Tix alloys, consisting of magnetic Nd2Fe14B phase and soft magnetic phases, were investigated. The effect of titanium addition on the structure and magnetic properties was studied. It was found that 2–4 at% Ti addition leads to substantial increase of the coercivity and maximum energy product, maintaining the remanence unchanged. The highest properties: Jr=0.81 T, JHc=907 kA/m, (BH)max=99 kJ/m3, were achieved for the Nd9Fe73B14Ti4 alloy. This effect we attribute to the formation of fine and homogeneous grain structure and a change of the phase morphology in the Ti-containing alloys. The initial magnetization curve indicates a change of the coercivity mechanisms giving rise to pinning of domain walls, which is caused by reduction of the crystallite size.

Effects of titanium addition on microstructure and wear resistance of hypereutectic high chromium cast iron Fe–25wt.%Cr–4wt.%C

A finer microstructure generally helps to increase the wear resistance of materials. It was reported that Ti could act as an inoculant to generate fine microstructure for white cast iron, one of widely used in industrial materials. To confirm this, we investigated influences of Ti addition (up to 6 wt.%) on microstructure of a hypereutectic high chromium cast iron (Fe–25wt.%Cr–4wt.%C). Ingot samples were prepared using an arc furnace by melting pieces of the cast iron with titanium powder. Microstructures of the samples were examined by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry and X-ray diffraction. It was demonstrated that the added titanium did not act as an inoculant to reduce the size of coarse primary carbides. Instead, as the titanium amount was increased, the cast iron changed from a hypereutectic microstructure to a hypoeutectic one due to the depletion of carbon that was consumed by Ti to form titanium carbides. When 2 wt.% Ti was added, the finest microstructure was achieved, which corresponded to the eutectic structure with mixed chromium carbides and titanium carbides. The eutectic structure exhibited the highest wear resistance and hardness due to the refined microstructure as well as the fact that an amount of chromium carbides were replaced by Ti carbides, which are harder than the former.

Studies on the effect of titanium addition on LiCoO2

The lithiated transition metal oxide has been used as the cathode materials for lithium ion rechargeable batteries. Among the various cathode materials, LiCoO2 has been widely used. There are lot of reports on the substituted LiCoO2 replacing small amount of Cobalt with other transition and nontransitional metals. Here, we focus on to a tetravalent transition metal atom such as titanium, as an addition in LiCoO2 and studied its performance. The titled cathode material was synthesized by solid-state reaction method. Thermogravimetric/differential thermal analysis, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and particle size analysis were carried out to assess the effect of addition of titanium on LiCoO2. Electrochemical studies were carried out by cyclic voltammetry and life cycle analyzer.

Effects of Ti Addition on As-cast γ Grain Structure in Hyper-peritectic Carbon Steel

Effects of titanium addition on as-cast austenite grain size in 0.2 mass% carbon steel cooled at 0.03°C/s has been studied. The average austenite grain size was reduced from 4.3 to 1.9 mm by increasing the titanium concentration from 0 to 0.13 mass%. Two different shapes of Ti(C, N) particles were observed in the solidified samples; one was a facet shape which were dispersed over the whole observation area and the other was a filmy shape, most of which were located on the austenite grain boundary. Thermodynamic calculations and EPMA analyses showed that the facet shaped Ti(C, N) particles crystallize at relatively high temperatures, while the filmy shaped ones form from the last solidifying liquid in the inter-dendritic regions at lower temperatures. The latter Ti(C, N) is considered to provide the grain refinement effect of austenite grain structure. The grain refinement effects of titanium are further discussed by comparing the results of 0.2 mass% carbon steel with those of 0.45 mass % one, which supports the substantial effect of the filmy shaped Ti(C, N) on the as-cast austenite grain structure.

Effect of titanium addition on the microstructure and inclusion formation in submerged arc welded HSLA pipeline steel

The effect of titanium addition on the SAW weld metal microstructure of API 5L-X70 pipeline steel was investigated. The relationship between microstructure and toughness of the weld deposit was studied by means of full metallographic, longitudinal tensile, Charpy-V notch and HIC tests on the specimens cut transversely to the weld beads. The best combination of microstructure and impact properties was obtained in the range of 0.02–0.05% titanium. By further increasing of titanium content, the microstructure was changed from a mixture of acicular ferrite, grain-boundary ferrite and Widmanstätten ferrite to a mixture of acicular ferrite, grain-boundary ferrite, bainite and ferrite with M/A microconstituent. Therefore, the mode of fracture also changed from dimpled ductile to quasi-cleavage. The results showed an increase in the titanium content of inclusions with increased titanium levels of weld metal. Titanium-base inclusions improve impact toughness by increasing the formation of acicular ferrite in the microstructure. No HIC susceptibility was found in the weld metals with titanium contents less than 0.09%.

Effect of titanium addition on crystallization kinetics of lithium borosilicate glass

Crystallization studies of glass samples [35 mol% Li 2O–18 mol% SiO 2–47 mol% B 2O 3 with adding x mol% TiO 2] where x = 0, 0.1, 0.5, 2 and 3 mol% TiO 2, were conducted by the use of the non-isothermal differential thermal analysis (DTA) and the isothermal differential scanning calorimeter (DSC) techniques. Both techniques were used to study the crystallization process. Two different glass transformation peaks and one-crystallization peak temperatures were identified and the transformed fractions were determined as a function of time. The JMAK equation was used to determine the mechanisms that govern the nucleation and growth. Both the rate of growth, k, and the activation energy, E, for the crystallization process with titanium content was calculated. It was found that the values of E, as well as the rate of growth, k, depend on the influence of titanium oxide in the glass network as a modifier or as a former and the titanium content. The values of the Avrami parameter, n, were calculated using the both techniques for the investigated glass samples and were in excellent agreement. Both techniques concluded that, the crystallization mechanism could depend on the influence of the titanium in the glass network. The process of nucleation and growth rate depends on the titanium content.

Improvement of the magnetic properties of low-neodymium magnets by minor addition of titanium

Rapidly solidified nanocomposite Nd 9Fe 77− x B 14Ti x alloys, consisting of magnetic Nd 2Fe 14B phase and soft magnetic phases, were investigated. The effect of titanium addition on the structure and magnetic properties was studied. It was found that 2–4 at% Ti addition leads to substantial increase of the coercivity and maximum energy product, maintaining the remanence unchanged. The highest properties: J r=0.81 T, J H c=907 kA/m, (BH) max=99 kJ/m 3, were achieved for the Nd 9Fe 73B 14Ti 4 alloy. This effect we attribute to the formation of fine and homogeneous grain structure and a change of the phase morphology in the Ti-containing alloys. The initial magnetization curve indicates a change of the coercivity mechanisms giving rise to pinning of domain walls, which is caused by reduction of the crystallite size.

Durability of Titanium/Dicalcium Silicate Composite Coatings in Simulated Body Fluid

Titanium/dicalcium silicate composite coatings with different ratios (weight ratios as Ca2SiO4: Ti = 3:7, 5:5, 7:3) were prepared by plasma spraying. Effects of titanium addition on coating properties, such as bonding strength, flexural modulus, and dissolution in simulated physiological environment, were studied. Results showed that the bonding strength between coating and Ti-6Al-4V substrate increased with increase of titanium content in the composite coatings. It was explained by the narrowed dissimilarity of thermal expansion coefficients between the coatings and substrates. Degradation of mechanical properties after immersion in simulated body fluid was also studied. The dissolution of dicalcium silicate in the composite coatings resulted in the decrease of flexural strength and flexural modulus of the coatings in the simulated physiological environment. The higher titanium content in the composite coatings, the stabler are the composite coatings in the physiological environment.

Effect of titanium additives on the microstructure of melt-spun CuCr ribbons

Microstructure and resistivity of ribbons from melt-spun CuCrTi alloys are studied in the initial state and after annealing. Lattice periods of the copper matrix and of chromium inclusions are determined. Thermodynamic analysis of processes occurring in solidification of the alloys is performed.

Effects of titanium addition on the microstructure of carbon/copper composite materials

Carbon(C)/copper(Cu)-based materials with high thermal conductivity and good stability at high temperatures were developed by adding a small amount of titanium, which has a low enthalpy of alloy formation with C and Cu. The isotropic fine-grained nuclear grade graphite and felt type C/C composite, which were impregnated by Cu and titanium, provided 1.3 times higher thermal conductivity at 1200 K than the original carbon materials. Microstructural analysis showed that the increase of thermal conductivity is due to the formation of titanium compounds at the C/Cu interface. These carbon-based materials could be a candidate material for the plasma facing components of fusion devices.