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Micron‐sized graphite particles additions to Al2011 alloy were investigated to know their impact on mechanical properties. The stir cast method was used to manufacture the Al2011 alloy with 2 and 4 wt% of graphite particles reinforced composites. The microstructural analysis and mechanical properties of the synthesized composites were tested. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) spectrums were used to characterize the microstructure of the samples that were obtained from the casting. SEM micrographs indicated the homogeneous distribution of particles and the EDS patterns confirmed the presence of graphite particles. Al2011 alloy hardness was decreased with the addition of graphite particles. Further, with the addition of 2 and 4 wt% of graphite particles in the Al2011 alloy, the ultimate tensile and yield strengths of composites were increased with increase in elongation. SEM micrographs of tensile fractured surfaces were used to study the various fractured behaviors in the Al2011 alloy‐graphite composites. [ABSTRACT FROM AUTHOR]

In the current scenario, many researchers aspire to develop biodegradable material for biomedical implant applications. Magnesium (Mg)-based alloys are most promising materials since they have mechanical properties similar to human bone. In this study, Mg alloy AZ31 matrix was reinforced with a seashell powder (2 wt.%) and zirconium dioxide (10 wt.%) using bottom pouring stir casting furnace. Scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) images confirms the proper distribution of reinforcement throughout the matrix. This study analyzed the influence of WEDM process parameters for the material removal rate (MRR) and surface roughness (SR) of the proposed composite. According to Taguchi's L9 (3 3) orthogonal array the machining was performed to investigate the ideal machining parameters with a range of pulse current (I p) 6–8 amps, pulse-on time ( T on ) 5–15 μ s and pulse-off time ( T off ) 10–30 μ s, respectively. Analysis of variance (ANOVA) result confirms that I p (45.86%) has the most influencing parameter affecting the MRR and SR, followed by T on (25.10%) and T off (17.19%), respectively. Furthermore, Technique for Order Preference by Similar Ideal Solution (TOPSIS) and desirability approach was employed to find the optimal parameter combinations to attain the best combined output responses. [ABSTRACT FROM AUTHOR]

Magnesium-based alloys were more prevalent in automobile applications owing to their mechanical properties, low mass, and density. However, its poor mechanical properties are restricting its applications. Therefore, the present study focuses on improving the mechanical properties of AZ31D alloy by reinforcing silicon carbide (SiC) and graphite (Gr) nanoparticles with weight fractions of 2%, 4%, and 6% using stir-casting technique. The microstructure analysis was performed using a scanning electron microscope. The elemental analysis was confirmed using energy-dispersive spectroscopy, and X-ray diffraction was used to study various phases in the nanocomposites. Further, the mechanical properties, such as microhardness, ultimate tensile strength, yield strength, and compression strength of the nanocomposites, were significantly improved by 53%, 59%, 62%, and 82%, respectively, as compared with base alloy. [ABSTRACT FROM AUTHOR]

Various electrochemical techniques were used to study the corrosion behaviour of the CNT-reinforced NiAl alloys under NaCl and Na2SO4 environments. The potentiodynamic polarization curves revealed activation Tafel behaviour when the NiAl alloy specimens were immersed in NaCl solution while passivation followed by slight development of transpassivation resulted under Na2SO4 environment. The reinforcement of pure NiAl alloy with up to 1.0 wt.% CNT increased the corrosion rate from 0.10 to 0.63 mm/yr under NaCl environment, while under Na2SO4 environment, the corrosion rate increased from 0.04 to 0.12 mm/yr. The observed increase in corrosion rate with an increase in CNT reinforcement (under both NaCl and Na2SO4 environments) suggested that the reinforcement of NiAl alloys with CNT reduced the corrosion resistance of NiAl. The X-ray diffraction analysis revealed that the corrosion products consisted of oxides including Al2O3 under NaCl environment, while scanning electron microscope analysis showed a porous passive layer on the surface of the alloy specimens immersed in Na2SO4 solution. [ABSTRACT FROM AUTHOR]

In this research work, fabrication of Al alloy metal matrix composites (MMCs) reinforced with electroless Ni-P-coated Al2O3 is carried out using the stir-squeeze casting method. Scrap Al alloy wheels as matrix materials and Al2O3 particles as reinforcements are used to develop the MMCs. The Ni-P coating on Al2O3 particles is carried out using an electroless process to improve mechanical and tribological properties by increasing the bonding strength between the ceramic particles and the matrix material. A pre-treatment process on Al2O3 particles is done before the electroless Ni-P coating. To analyse the properties, the composites are fabricated in three different variations, i.e. as-cast scrap Al alloy, scrap Al alloy with uncoated Al2O3 (5 wt%), and scrap Al alloy with coated Al2O3 (5 wt%). Metallurgical properties are analysed using an optical microscope (OM), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDAX), and X-ray diffraction (XRD). The test results show that the porosity is reduced by 15.45% in a composite reinforced with coated Al2O3 compared to the as-cast scrap Al alloy. Also, the mechanical properties such as hardness, tensile strength, and impact strength are improved significantly by 15.2, 23, and 31.25%, respectively. Reduction of 31.47% in specific wear rate and 7.34% in coefficient of friction are achieved in the composite reinforced with coated Al2O3 particles compared to the as-cast scrap Al alloy. The compressive strength is decreased significantly with the addition of uncoated Al2O3 particles. After the addition of coated Al2O3, the compressive strength of the composite is increased compared with the uncoated Al2O3-reinforced composite. [ABSTRACT FROM AUTHOR]

Metal matrix composites (MMCs) are a special class of materials carrying combined properties that belongs to alloys and metals according to market demands. Therefore, they are used in different areas of industry, and the properties of this type of material are useful in engineering applications. Machining of such composites is of great importance to finalize the fabrication process with improved part quality. However, the process implies several challenges due to the complexity of the cutting processes and random material structure. The current study aims to examine machinability characteristics. Effects of turning a metal matrix composite built of Al2O3 sinter, saturated with an EN AC-44000 AC-AlSi11 alloy, are presented in this paper. In the present study, a turning process of new metal matrix composites was carried out to determine the state-of-the-art material for various engineering applications. During the turning process, the cutting forces, a tool's wear, and surface roughness were investigated. Further, the SEM (scanning electron microscope) analysis of cutting inserts was performed. The influence of MMC structure on the machining process and surface roughness was studied. The Al2O3 reinforcements were used in different graininess. Effects of conventional turning of the metal matrix composite with Al2O3 sinter of FEPA (Federation of European Producers of Abrasives) 046 and FEPA 100 grade were compared. Results analysis of these tests showed the necessity of continuing research on turning metal matrix composites built of an AlSi alloy and Al2O3 ceramic reinforcement. The study showed the properties of MMCs that influenced machinability. In this paper, the influence of feed rate's value on surface roughness was carried out. The significant tool wear during the turning of the MMC was proved. [ABSTRACT FROM AUTHOR]

The majority of the properties required for orthopedic implant operation are demonstrated by magnesium and its alloys, however, the metal degrades rapidly in the body’s environment. Therefore, a magnesium-based metal matrix composite capable of safely and gradually degrading in the body within the required healing time is required, thereby eliminating the need for a second surgery. The degradability of this newly formed alloy was done via corrosion test of this alloy in various corrosive media namely, H20, NaCl, Urine, Blood, and Plasma. Three samples A (50% reinforcement), B (25% reinforcement), and C (No reinforcement) of grade AZ31B Magnesium alloy and Calcium Carbonate powder reinforcement were developed via stir-casting technique. The impact strength of this alloy was carried out by using Charpy Impact Tester, while the microstructural characterization was determined by Scanning Electron Microscope (SEM). [ABSTRACT FROM AUTHOR]

Aluminium alloys reinforced by nanoparticles are widely utilized in space vehicles, automotive components and industrial applications due to the unique characteristic of high stiffness to weight ratio. In this research, aluminium alloy 8011-TiC (Titanium Carbide) composites with a various weight percentage of reinforcement such as 5%, 7% and 9% wt.% were produced through stir casting technique. The contribution and uniform dispersion of TiC nano particles in Al 8011 was investigated through microstructural examination, mechanical and tribological behaviour. To sew up the uniform distribution of reinforcement particles over composite metal matrix alloy was investigated using Scanning and Optical Electron Microscope (OEM & SEM) depiction. The pattern of TiC content in the Al8011 alloy was observed through X-ray diffraction technique. Also, specimens are exposed to wear test as per ASTM G99 standard and the weight loss method is adopted. The result exhibits that tensile, yield strength properties and microhardness of nanocomposites particles to about increases by 35%, 170% and 150% respectively. The mechanical properties and wear resistance of 7% TiC yields better results compared with Al 8011 alloy and other compositions of augmentations. [ABSTRACT FROM AUTHOR]

The aluminium alloy will improve its strength further with addition of reinforcement on considering its applications to produce much lighter weight to high strength parts. This work examines the addition of silicon carbide at varying levels of 12%, 14% and 16% in 6061 aluminium alloy. In addition, magnesium and copper are added to aid the strength of the Aluminium Metal Matrix Composite. The process parameters are optimized for the wear rate of the composites through Taguchi technique together with design of experiments. The percentage of SiC addition, load applied (30N, 60N and 90N) and sliding distance (500m, 1000m and 1500m) are the parameters taken into consideration for this wear analysis. It was observed that sliding distance was the most influencing factor, among others, while investigating the wear behaviour with ANOVA. Microstructure analysis performed with a scanning electron microscope on worn surfaces shows that SiC particles influence the wear rate of the composites. [ABSTRACT FROM AUTHOR]

This paper details the synthesis of Al7475 alloy with 8% wt. of nano B4C particulate metal matrix composites using the liquid metallurgy technique. Scanning electron microscope (SEM) of the synthesized composites demonstrates the uniform dispersion of the reinforced nano B4C particles throughout the matrix. EDS spectrums confirmed the various elements present in Al7475-B4C composites. Hardness, tensile and compression tests were carried out to find out the impact of nano B4C on various mechanical properties of the composites. Synthesized composites had a greater hardness, tensile and compression strength with the incorporation of B4C particles. Tensile failure analysis was studied using SEM images of fractured surfaces. [ABSTRACT FROM AUTHOR]

AZ61 magnesium alloy metal matrix composites (MMCs) with different weight percentages (0, 1 and 2) of micro-silicon carbide particles (SiCp) were fabricated using stir casting method. Effects of SiCp on the microstructural distributions, mechanical and fatigue properties, and fracture surfaces have been investigated. The microstructural observations of as-cast MMCs unveil the existence of primary α-Mg phase and the presence of large amount of β-Mg17Al12 secondary phase at grain boundary. The specimens are subjected to homogenization heat treatment at 410 °C for 24 h; the β-Mg17Al12 phases are significantly dissolved in the matrix grain boundaries which enhance the ductility and decrease the hardness compared with the as-cast materials. The addition of SiCp reinforcement led to improved yield strength (YS) and ultimate tensile strength (UTS) of AZ61/SiCp composite compared to the unreinforced alloy. The maximum values of YS and UTS have been attained at AZ61/1wt%SiCp composites. The enhancement of YS and UTS was due to the presence of a uniformly distributed reinforced SiCp, which depends on grain refinement of the matrix and strong interfacial bonding between the matrix and reinforcement. In the case of fatigue test results, the addition of SiCp reduced the fatigue life and strength of AZ61 alloy composite. However, addition of 1wt%SiCp showed good mechanical and fatigue properties compared to pure AZ61 magnesium alloy and AZ61/2wt%SiCp composite. Furthermore, the effects of addition of SiCp on the mechanical and fatigue properties of the composite were confirmed by using the scanning electron microscope observation of fracture surfaces. [ABSTRACT FROM AUTHOR]

The scope of the present study is focused on high-entropy alloy (HEA), a new type of alloy system-reinforced aluminium metal matrix composite (AMMC) development. The novel metal–metal composite is fabricated through powder metallurgy by reinforcing prepared AlCoCrCuFe HEA particles with aluminium. Headed for identifying the effect of HEA on aluminium, weight percentage of HEA is varied from 0 to 15% with an equal interval of 3%. By using X-ray diffractometer, phase constituents of HEA and Al base material are analysed besides the fact that the scanning electron microscope is utilized for morphology analysis of HEA particles and AMMC. Density of the aluminium increases gradually with the increase in HEA content due to higher density of reinforcements, and maximum micro-hardness of 71.3 HV is attained for 15% HEA reinforcement addition which is 37.6 HV for unreinforced aluminium. Among the various predictive methodologies, the density and hardness of Al–AlCoCrCuFe metal–metal composite are found close to the values predicted by the Reuss and Voigt model, respectively. Decrease in wear rate was found for aluminium MMC with the increase in HEA reinforcement addition. [ABSTRACT FROM AUTHOR]

In the present study, effect of ZrC vol.% on mechanical properties of AA6061 metal matrix composites (MMCs) produced via stir casting technique was investigated. The vol.% of ZrC particles was varied as 5,10 and 15. The composites were characterized for its microstructure and mechanical properties and their relationships were obtained. The scanning electron microscope (SEM) images revealed uniform distribution and good bonding between the AA6061 alloy and the ZrC particles. The mechanical properties of the AA6061 alloy was found to significantly improve with the addition of ZrC particles from 5 to 15 vol.%, the hardness increased from 32 to 68 HV, yield strength increased from 50 to 86 MPa and the ultimate tensile strength increased from 118 to 165 MPa. However, the % of elongation of the composite samples decreased with 15 vol.% addition of ZrC particles. Sliding wear behaviour of the composites was investigated using a pin-on-disc wear tester at a load of 9.8 N and addition of ZrC particles was significantly found to reduce the wear rate of AA6061 alloy. [ABSTRACT FROM AUTHOR]

Raw material handling areas in an integrated steel plant experience severe wear of engineering components. The use of hardfacing plates is one of the ways to combat this problem. Three commercial hardfacing Fe-Cr-C alloys of varying Cr content were deposited on mild steel base plate and studied in this work. Abrasive wear tests were conducted by using pin-on-disk tribometer in accordance with the ASTM G99. Microstructural characterization was done by using optical and scanning electron microscopes. Energy- and wavelength-dispersive spectroscopies were carried out to study the carbide type and distribution in the hardfaced deposit. It was observed that wear resistance increases with increasing Cr content in the alloy. Along with hardness, morphology and type of carbide are also important factors to decide the wear resistance. An attempt has been made to corelate the chemical composition, carbide morphology, and macrostructural features with wear properties of hardfacing alloys. [ABSTRACT FROM AUTHOR]

The heterogeneous interface constituted by Cu and Al were diffusion-bonded with CuZn alloy fibre interlayer under different bonding parameters, which was compared with directly bonded Cu/Al interface to analyze the effects of the different intermetallic compounds (IMCs) occurred at the joining interface on the interface mechanical properties. The interface microstructure was analyzed by scanning electron microscope (SEM), the compositions profiles across the joining interface were measured by energy dispersive spectroscopy (EDS), the phase and grain in the bonding interface of a Cu/Al bond were carefully investigated via electron backscatter diffraction technique (EBSD), the results show that the interface phase of Cu/Al composites grows irregularly, which leads to the low uniformity of interface properties. By adding CuZn alloy fibre, the interface of Cu/Al shows cellular skeleton and promotes the uniform diffusion of interface. When the bonding time was 570 °C for 60 min, the average shear strength of Cu/CuZn/Al interface reached 60.7 MPa. Compared with Cu/Al interface, the standard deviation of shear strength decreased from 18.7 to 1.6, and the variance decreased from 3.7 to 1.1. • The diffusion of Cu and Al was promoted by the introduction of Zn. • CuZn alloy can improve the interface homogeneity of large area Cu/Al composites. • When CuZn alloy fibre was added, the fracture mode changed to mixed fracture. • The bonding time has a great effect on the uniformity of the interface. [ABSTRACT FROM AUTHOR]

This paper is aimed at investigating the corrosion behavior of Pure and Zinc-graphite particles with percentage of 1, 3, and 5%, respectively. The composites were fabricated by powder metallurgy method. Corrosion tests were performed according to ASTM standard. Corrosion rate was calculated and it is found that in all cases the corrosion rate was decreasing with the increase in exposure time. Meanwhile, the microstructure of composites was imaged and analyzed using optical microscope and scanning electronmicroscope. It is observed that the best corrosion resistance was zinc with 1%Graphite while Zinc with 3%and 5%Graphite composites did not enhance the corrosion resistance comparing to pure Zinc. [ABSTRACT FROM AUTHOR]

Epoxy resin attached to a fatigue fracture surface of Ti–Al–Nb alloy was removed using a removal method for hardly soluble organic material attached to metallic material, which has been developed by the author. In the removal method process, the epoxy resin attached to the fracture surface was treated with an organic solvent, `tetrahydrofuran', and cold concentrated sulfuric acid of nearly 100% purity. After the epoxy resin was removed from the fracture surface with the removal method, damage of the microscopic feature of the fracture surface was investigated using a scanning electron microscope (SEM). For the first time, the degree of the removal of the epoxy resin with the method was investigated by energy dispersive X-ray spectroscopy (EDS) in this research. After the removal, no damage of the fracture surface was found with SEM observation. In addition, C Kα derived from the epoxy resin was not detected with the EDS after removal. The result of the EDS analysis clarified that the epoxy resin was completely removed with the removal method. [ABSTRACT FROM PUBLISHER]

Abstract: Dry sliding wear of Al–4Cu–xTiB2 (x =0, 2.5, 5, 7.5 and 10wt.%) in situ composites have been studied in the peak-aged condition using a pin-on-disc wear testing machine at different loads. The composites were prepared by the reaction of a mixture of K2TiF6 and KBF4 salts with molten alloy. The results indicate that TiB2 particles markedly improve the wear performance of the Al–4Cu alloy. The wear resistance increases with increase in the amount of TiB2. The load bearing capacity of the alloy during wear increases in presence of TiB2 particles. Study of the wear surfaces and debris of both alloy and composites using the scanning electron microscope suggests that the improvement in wear resistance is mainly due to the formation of finer debris. [Copyright &y& Elsevier]

In the present investigation, an attempt has been made to evaluate the wear rate of ZA-27 alloy composites reinforced with fly ash particles from 1 to 3 wt% in steps of 1 wt%. The compo-casting method has been used to fabricate the composites using Raichur fly ash of average size 3-5 microns. The wear specimens are tested under dry conditions using a pin-on-disc sliding wear testing machine with wear loads of 20-120 N in steps of 20 N, and the sliding distances in the range of 0.5 km to 2.5 km. The results indicate that the wear rate of the composites is less than that of the matrix alloy and it further decreases with the increase in fly ash content. However, the material loss in terms of wear rate and wear volume increases with the increase in load and sliding distance, both in the cases of composites and the matrix alloy. An increase in the applied load increases the wear severity by changing the wear mechanism from abrasion to particle-cracking induced delamination wear. It is found that with the increase in fly ash content, the wear resistance increases monotonically. The observations have been explained using scanning electron microscope (SEM) analysis of the worn surfaces of the composites. [ABSTRACT FROM AUTHOR]

Abstract: Dilute Te-doped GaSb alloys have been prepared by the vertical feeding method (VFM) using both casting and feeding configurations. The structural and optical properties of the samples were characterized by etching, X-ray diffraction and cathodoluminescence in the scanning electron microscope. The obtained results confirm the variation of the segregation coefficient k observed in previous VFM Te-doped GaSb experiments. The increase of k and the grain structure refinement are attributed to the increase of the interface velocity. The feeding configuration of the VFM seems to be the most appropriate one to control segregation and grain size for Te-doped GaSb alloys. [Copyright &y& Elsevier]

Abstract: The effects of mechanical ball-milling on the hydriding/dehydriding behaviors of La1.8Ca0.2Mg14Ni3 alloy were investigated. The time of ball-milling under an argon atmosphere is 10, 15 and 20h, respectively. The changes in phase structure and morphology of the samples were analyzed through XRD and scanning electron microscope (SEM). The results show that mechanical ball-milling can improve the hydrogen absorption/desorption kinetics of La1.8Ca0.2Mg14Ni3 alloy. The milled alloys of La1.8Ca0.2Mg14Ni3 show much better hydriding/dehydriding behaviors than the as-cast alloy. Among the alloys studied, the alloy milled for 20h shows the best overall property. [Copyright &y& Elsevier]

Abstract: The cracking behaviour of indented areas in monolithic Mo5Si3 and segregation in Cr-alloyed Mo5Si3 have been studied by electron back-scattering diffraction (EBSD) in a scanning electron microscope (SEM). Vickers indentation of Mo5Si3 indicates preferred cleavage across the [001] direction, resulting in chipping if the indent is normal to the (001) plane. The other two alloyed Mo5Si3-based compounds studied in this work, i.e. Mo3Cr2Si3 and Mo3Ti2Si3, behave differently during heat treatment. Mo3Cr2Si3, on the one hand, shows unexpected additional X-ray reflections together with broadening of reflections after annealing, when compared to its as-cast condition. Observations of increased segregation upon annealing are made, presumably by a separation into Cr-lean and Cr-enriched (Mo,Cr)5Si3, especially in the <100> directions according to EBSD. Segregation of Cr is linked to additional reflections in X-ray diffraction (XRD). Mo3Ti2Si3, on the other, seems to be in chemical equilibrium in the as-cast state according to energy dispersive spectrometry (EDS) measurements, and there is little difference in XRD between as-cast and heat treated alloys. [Copyright &y& Elsevier]

Direct observation on fatigue crack growth behavior in SiC (SCS-6) fiber-reinforced Ti-15-3 alloy matrix composite subjected to a constant tension–tension loading mode was performed by scanning electron microscope using a single edge-notched specimen in vacuum at room temperature and 550 °C. The fatigue crack growth rate at 550 °C was lower than that at room temperature, and the difference between the fatigue crack growth rates at room temperature and 550 °C increased with increasing fatigue cycles. The crack opening displacement at 550 °C was smaller than that at room temperature when the crack length exceeded a definite value, though the interface friction stress between the fiber and matrix at elevated temperature was much smaller than that at room temperature. The above results were explained qualitatively by a residual stress mechanism at the crack front and the crack closure behavior at crack wake, which could be produced by matrix creep asymmetry in tension and compression at elevated temperature during each fatigue cycle. [Copyright &y& Elsevier]

The effects of SiC particle size and alloy elements such as Si, Cu and Ti on the response to aging treatment and wear resistance in Al-5Mg-X(Si,Cu,Ti)/SiCp composites fabricated by pressureless infiltration method have been investigated by hardness tester, scanning electron microscope (SEM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC) and wear tester. The Al-5Mg-0.3Si-0.1Cu-0.1Ti/SiCP composites had better wear resistance property among Al-5Mg-X(Si,Cu)/SiCP composites. The wear resistance property of all the composites was enhanced after aging at 170°C for 8 hrs due to precipitates of β'(Mg2Si) phase. The wear resistance property of the composite as-fabricated with 50 μm size of SiC particle is superior to that of the composite as-fabricated with 100 μm SiC size of particle. In Al-5%Mg alloy aged at 170°C for 8 hrs, the frictional seizure appeared more than abrading speed of 1.90 m/s, but in Al-5Mg-(Si,Cu,Ti)/SiCP composites aged at 170°C for 8 hrs, the frictional seizure was not found at abrading speed ranging from 0.5 m/s to 4.3 m/s. [ABSTRACT FROM AUTHOR]

In this investigation, the extensive wear behaviour of materials was studied using SiC reinforced magnesium alloy composites fabricated through the stir casting process. The wear properties of AZ91 alloy composites with a small variation (i.e., 3%, 6%, 9% and 12%) of SiC particulates were evaluated by varying the normal load with sliding velocity and sliding distance. The worn surfaces were examined by scanning electron microscope to predict the different wear mechanisms on the pin while sliding on the hard disk in the dry sliding wear test condition. The microhardness of the SiC reinforced AZ91 composites was found to be more than the un-reinforced AZ91 alloy. Pins tested at load 19.62 N, and 2.6 m/s exhibited a series of short cracks nearly perpendicular to the sliding direction. At higher speed and load, the oxidation and delamination were observed to be fully converted into adhesion wear. Abrasion, oxidation, and delamination wear mechanisms were generally dominant in lower sliding velocity and lower load region, while adhesion and thermal softening/melting were dominant in higher sliding velocity and loads. The wear rate and coefficient of friction of the SiC reinforced composites were lower than that of the unreinforced alloy. This is due to the fact of higher hardness exhibited by the composites. The wear behaviour at the velocity of 1.39 m/s was dominated by oxidation and delamination wear, whereas at the velocity of 2.6 m/s the wear behaviour was dominated by abrasion and adhesion wear. It was also found that the plastic deformation and smearing occurred at higher load and sliding velocity. [ABSTRACT FROM AUTHOR]