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Microstructure, Texture, Mechanical and Ballistic Properties Correlation of a Hot Rolled and Peak Aged AA-7017 Alloy Plate at Surface and Centre  [PDF]
Pradipta Kumar Jena, Kandikattu Siva Kumar, Rajiv Kumar Mandal, Ashok Kumar Singh
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.813073
Abstract: The present work describes microstructure, texture, mechanical and ballistic properties correlation of a hot rolled and peak aged AA-7017 alloy plate at surface and centre. Both the microstructures and textures are different on the surface and centre of the plate. The surface of the plate shows recrystallized grains and a weak over all texture. The centre of the plate displays elongated grains and a sharp texture. Tensile properties, hardness and impact toughness are evaluated at surface and centre of the plate. It is observed that strength and hardness is high at centre, whereas ductility and impact toughness is more at the surface. Ballistic properties of the plate at centre and surface are measured by impacting against two different 7.62 mm deformable projectiles. The plates impacted on the surface shows better ballistic resistance. Ballistic performance of the plate at surface and centre has been correlated with the microstructure, texture and mechanical properties.
Variations in Wear Resistance of a Novel Triboalloy Pseudoelastic TiNi Alloy-with Respect to its Pseudoelasticity and Hardness

材料科学技术学报 , 2001,
Abstract: It has recently been found that TiNt shape memory alloy has another attractive property, high resistance to wear. The wear resistance of this alloy benefits from its pseudoelasticity (PE). It has, however, been noticed that other mechanical properties also affect the wear resistance, especially the hardness. Research was conducted to investigate the correlation between the wear resistance and both the PE and hardness. It has been demonstrated that when the PE is high, lower hardness leads to higher wear resistance.
Estimation of cyclic stress-strain curves for low-alloy steel from hardness  [PDF]
R. Basan,M. Franulovi?,S. Smokvina Hanza
Metalurgija , 2010,
Abstract: This article describes investigations into the existence of correlation between experimentally determined cyclic parameters and hardness of quenched and tempered representative low-alloy steel 42CrMo4. A good correlation was found to exist between cyclic strength coefficient K’ and Brinell hardness HB, but not between cyclic strain hardening exponent n‘ and hardness HB. Nevertheless, good agreement between calculated and experimental cyclic stress-strain curves shows that cyclic parameters i.e. cyclic stress-strain curves of the investigated steel can be successfully estimated from its hardness.
Hardness and electrochemical behavior of ceramic coatings on Inconel
Journal of Electrochemical Science and Engineering , 2012,
Abstract: Thin films of ceramic materials like alumina and silicon carbide are deposited on Inconel substrate by pulsed laser deposition technique using Q-switched Nd: YAG laser. Deposited films are characterized using UV-visible spectrophotometry and X-ray diffraction. Composite microhardness of ceramic coated Inconel system is measured using Knoop indenter and its film hardness is separated using a mathematical model based on area-law of mixture. It is then compared with values obtained using nanoindentation method. Film hardness of the ceramic coating is found to be high compared to the substrates. Corrosion behavior of substrates after ceramic coating is studied in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The Nyquist and the Bode plots obtained from the EIS data are fitted by appropriate equivalent circuits. The pore resistance, the charge transfer resistance, the coating capacitance and the double layer capacitance of the coatings are obtained from the equivalent circuit. Experimental results show an increase in corrosion resistance of Inconel after ceramic coating. Alumina coated Inconel showed higher corrosion resistance than silicon carbide coated Inconel. After the corrosion testing, the surface topography of the uncoated and the coated systems are examined by scanning electron microscopy.

XIAO Kai,YAN Yigong,LEI Liangcai,DU Yuanlong,

腐蚀科学与防护技术 , 2002,
Abstract: In this article,the electrochemical performance of Pd-Ag alloy electrode in KOH alkaline solution was studied.The reaction mechanism of Pd(Pd-Ag)-H 2 system was discussed and the quantitative relationship between sensor response and hydrogen content was acquired.Pd-Ag alloy electrode is suitable for using as selective catalytic anode of hydrogen sensor.The electrochemical hydrogen sensor based on Pd-Ag alloy anode exhibits high sensitivity and good repetition.
Surface roughness investigation and hardness by burnishing on titanium alloy  [PDF]
S. Thamizhmnaii,B. Bin Omar,S. Saparudin,S. Hasan
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: Burnishing is a chip less machining process in which a rotating roller or ball is pressed against metal piece. It is a cold working process and involves plastic deformation under cold working conditions by pressing hard. The burnishing process help to improve surface roughness and hardness.Design/methodology/approach: The methodology adopted was using a multi roller on square titanium alloy material by designing various sliding speed/ spindle speed, feed rate and depth of penetration.Findings: The roller burnishing is very useful process to improve upon surface roughness and hardness and can be employed. It will help to impart compressive stress and fatigue life can be improved. The titanium alloy is a difficult to machine material and burnishing is difficult process for this grade material. A low surface roughness and high hardness was obtained for the same spindle rotation, feed rate and depth of penetration.Research limitations/implications: There are some limitations in increasing the operating parameters. It may develop flaw and micro cracks on the surface.Originality/value: The value of the work lies in using the results for other researches to follow and further can be continued on fatigue life.
The effects of microalloying with silicon and germanium on microstructure and hardness of a commercial aluminum alloy
Journal of the Serbian Chemical Society , 2003,
Abstract: The effect of small additions of Si and Ge on the microstructure and hardness was investigated during aging of a commercial 2219 aluminum alloy. It was found that for the same level of microalloying in alloy 2219SG (containing Si and Ge), a maximum hardness was achieved 3 times faster than in alloy 2219S (without Ge). The accelerated precipitation kinetics is a consequence of the presence of fine Si Ge particles, serving as heterogeneous precipitation sites for q strengthening particles.
Electrochemical Impedance Study of Zinc Yellow Polypropylene-Coated Aluminum Alloy  [PDF]
Zhi-hua Sun,Jian-ping Cai,Ming Liu,Feng Lu,Ni Zhang
International Journal of Corrosion , 2010, DOI: 10.1155/2010/528573
Abstract: Performance of zinc yellow polypropylene-coated aluminum alloy 7B04 during accelerated degradation test is studied using electrochemical impedance spectroscopy (EIS). It has been found that the zinc yellow polypropylene paint has few flaw and acts as a pure capacitance before accelerated test. After 336-hour exposure to the test, the impedance spectroscopy shows two time constants, and water has reached to the aluminum alloy/paint interface and forms corrosive microcell. For the scratched samples, the reaction of metal corrosion and the hydrolysis of zinc yellow ion can occur simultaneously. The impedance spectroscopy indicates inductance after 1008-hour exposure to the test, but the inductance disappears after 1344-hour exposure and the passivation film has pitting corrosion. 1. Introduction Organic coatings have been widely applied to control the corrosion of airplanes for many years [1, 2]. The performance of organic coatings, which generally relates to their barrier performance character against water, oxygen, and ions and to their good adhesion to substrate impeding delamination, seriously influences their protection efficiencies to metallic substrates [3, 4]. However, organic coatings can degrade under various service conditions and the degradation process of paints is complicated since it is affected by several factors, such as humidity, heat impact,ultraviolet (UV) radiation, salt fog, pollutants (like ), low temperature fatigue, and other exotic (like dust) [5, 6]. The degradation evaluation can be visual, mechanical, electrochemical, and so furth. The use of electrochemical techniques combined with accelerated tests has resulted in new information concerning the degradation mechanisms of organic coatings in corrosive environments [7, 8]. In particular, electrochemical impedance spectroscopy (EIS) has been shown to be very useful technique for the study of the performance of anticorrosive primers [9, 10]. Zinc yellow polypropylene primer has been widely used in aeronautical industry, and its EIS study has been carried out. But the research mainly focus on its impedance measurement with exposure time after immersion to certain solution, such as NaCl solution [11, 12], and the failure characteristics after exposure to accelerated test simulating the service conditions have not been investigated. In the present work, electrochemical impedance varieties of zinc yellow polypropylene-coated aluminum alloy 7B04 used in aircraft during accelerated test to simulate its service condition are studied using EIS, and the characteristics of corrosive failure
The Development of a Novel Gold Alloy with 995 Fineness and Increased Hardness
Madeleine du Toit,Elma van der Lingen,Lizelle Glaner,Rainer Süss
Gold Bulletin , 2002, DOI: 10.1007/BF03214837
Abstract: The mechanical properties and processing of a newly developed ternary Au-Sb-Co alloy with 995 fineness are discussed. The high gold content of this alloy (99.5 per cent) facilitates marking as 24 carat gold (orChuk Kam) in many countries. The alloy has a rich yellow colour, virtually identical to that of pure gold, and can be hardened to a peak hardness of 130 to 140 points on the Vickers hardness scale using a combination of cold work and a low temperature (250 to 300°C) ageing heat treatment. This hardness is comparable to that of cold-worked 22 carat yellow gold, and almost double the maximum hardness that can be obtained in pure gold. The 995 alloy is highly formable, and is amenable to casting, granulation, remelting, wire drawing, forming and rolling.
Effect of calcium content on the microstructure, hardness and in-vitro corrosion behavior of biodegradable Mg-Ca binary alloy
Harandi, Shervin Eslami;Mirshahi, Mohammad;Koleini, Shahriar;Idris, Mohd Hasbullah;Jafari, Hassan;Kadir, Mohammed Rafiq Abdul;
Materials Research , 2013, DOI: 10.1590/S1516-14392012005000151
Abstract: effect of calcium addition on microstructure, hardness value and corrosion behavior of five different mg-xca binary alloys (x = 0.7, 1, 2, 3, 4 wt. (%)) was investigated. notable refinement in microstructure of the alloy occurred with increasing calcium content. in addition, more uniform distribution of mg2ca phase was observed in a-mg matrix resulted in an increase in hardness value. the in-vitro corrosion examination using kokubo simulated body fluid showed that the addition of calcium shifted the fluid ph value to a higher level similar to those found in pure commercial mg. the high ph value amplified the formation and growth of bone-like apatite. higher percentage of ca resulted in needle-shaped growth of the apatite. electrochemical measurements in the same solution revealed that increasing ca content led to higher corrosion rates due to the formation of more cathodic mg2ca precipitate in the microstructure. the results therefore suggested that mg-0.7ca with the minimum amount of mg2ca is a good candidate for bio-implant applications.
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