Phase Transformations Microstructural Control

Phase Transformations Microstructural Control Phase transformations microstructural control 2xxx-series Aluminum Alloys Introduction: 2000 Series Aluminum Alloys: Principal alloying element is copper with minor additions of manganese and magnesium. This series of aluminum is the original heat treatable alloy group developed in the 1920s. The best known, most widely used heat treatable alloy for aircraft and aerospace is 2024. Can be spot and friction welded but not fusion welded (a few exceptions being tank structures in the Titan Missile). Has good formability in the annealed temper condition and some formability in the solution treated and aged condition, but needs intelligent application in complex designs. Has excellent fatigue properties when compared to other aluminum alloys, excellent strength to weight ratio. Good machinability. Poor resistance to corrosion without alclad layer or secondary chem film, anodize and/or prime and paint. Can be chem film and anodized readily. Other 2000 series alloys include 2017 seen widely in aluminum rivets, fasteners and screw machine parts and 2014 which is used heavily in forgings. These three alloys, 2024, 2014, and 2017 can be considered the foundations of aluminum aircraft, missiles and space vehicles during these past 75 years. Heat Treating Aluminum Alloys: (1) Example 2024: Aluminum alloys are not allotropic they do not undergo a phase or structure change like steels when heating. But if the right alloying additions are present they can be heat treated by solution heat treating and precipitation hardening. In the early days (1930s) solution heat treatment was referred to as ST, and many times precipitation hardening was referred to as aging. Solution heat treatment involves temperatures very close to the melting point of the aluminum alloy, usually 200 300 deg. below the melting point. The purpose is to provide enough thermal energy to dissolve, in a solid solution, the alloy elements present. In the case of 2024, the major alloy element is copper, and by taking the part to 920 deg. F, the copper present within the 2024 will dissolve or disperse uniformly throughout the solid aluminum part. This can be difficult to comprehend how can something dissolve and still be solid? As Einstein once said, everything is relative Without getting into the solid state physics of the metallurgical reactions, dissolution does occur but only at this high temperature. However, if you slowly cool down the part, the copper wants to come back out of solution. Here is where the important step of quenching takes place. Quenching is a very rapid cool down, using water, on the order of 500 600 deg. per second. Quenching locks in place all alloy elements that have been dissolved at the high solution heat treat temperature. Before the alloy additions can think about changing places and moving back out of solution wham! they are locked in place by the rapid quench cool down. The result is called a super saturated solid solution an unstable condition. Quenching is critical to proper solution heat treatment. Aging Precipitation Hardening can now happen under the right conditions. In the case of natural aging of 2024, or aging at room temperature, the dissolved copper slowly comes back out of solution over an extended time (96 hours minimum), forming CuAl precipitants. Precipitants or precipitated particles can be thought of as army commandos, coming from nowhere out of the sky to stand guard, strengthening the territory. Indeed the word precipitant comes from the weather term precipitation meaning to separate and fall from solution (clouds). Precipitated particles in heat treatable aluminum alloys strengthen the alloy by pinning or locking up numerous microstructural features in the aluminum. Other heat treatable alloys like 6061 and 7075 undergo very similar precipitation reactions, with the actual precipitated particles differing depending on whether zinc, magnesium, manganese, silicon or copper additions are present. The way that metallurgists control the formation of these precipitants will determine the mechanical and corrosion properties later. In the case of artificial aging or precipitation hardening, the previously solution heat treated and quenched parts are subjected to elevated temperatures (instead of room temperature) in the range of 225-375 deg. F over extended periods of time (4-24 hours). The precipitants formed and grown here are more controlled and substantial in nature, resulting in higher mechanical properties as compared to naturally aged conditions. Abstract: Recently, Aluminum and Aluminum alloys are broadly used in several fields of industries due to their properties such as, light weight (low density), good formability, good malleability, high electrical conductivity, high thermal conductivity and high corrosion resistance. In general, pure aluminum and its alloys still have many problems during using in the engineering applications; for example: unstable mechanical properties and relatively low strength . Therefore; adding alloying elements, and heat treatment are done to modify the microstructure and improve the mechanical properties of aluminum. The alloying elements could be classified as major and minor elements, microstructure modifiers or impurities, where the minor elements in some alloys may be major elements in other alloys. This report investigates the influences of copper as alloying element on aluminum alloys and then the microstructures mechanical properties relations in this regards. Introduction: Aluminum copper alloys are gaining huge industrial usage because of their outstanding combination of mechanical, physical properties. These properties involve high specific strength specially high temperature strength, high hardness. These properties obtained through addition of copper and other alloy elements and heat treatment ability of this series. Alloying elements are chosen according to their effects and suitability (1) Aluminium-Copper Alloys: Due to the wrought aluminum alloys designation system, aluminium copper alloys are designated 2xxx series. the major alloying element in this series is copper (Cu). 2xxx series could include manganese (Mn), magnesium (Mg), Silicon (Si), titanium (Ti), and nickel (Ni) as minor alloying elements. Table (1) shows the chemical compositions of some wrought aluminum-copper alloys (2xxx) (2): Table (1): chemical compositions of Al-Cu alloys Alloy Si% Cu% Mn% Mg% Ni% Ti% Other elements% 2011 0.4 max 5.0 6.0 Pb=0.4 Bi=0.4 2014 0.5 1.2 3.9 5.0 0.4 1.2 0.2-0.8 0.15 max 2017 0.2 0.8 3.5 4.5 0.4 1.0 0.4 0.8 0.15 max 2018 0.9 max 3.5-4.5 0.4-0.9 1.7-2.3 2024 0. 5 max 3.8 4.9 0.3 0.9 1.2 1.8 0.15 max 2025 0.5-1.2 3.9-5.0 0.4-1.2 0.15 max 2124 0. 2 max 3.8 4.9 0.3 0.9 1.2 1.8 0.15 max 2219 0. 2 max 5.6 6.8 0.2 0.4 0.02 0.1 V=0.1 Zr=0.18 2319 0. 2 max 5.6-6.8 0.2-0.4 0.1-0.2 V=0.1, Zr=0.18 Microstructure-Property Relationships: Copper which is the primary alloying element in the 2xxx series alloys increases the tensile strength, fatigue strength and hardness of aluminum alloys because of the effect of solid solution hardening. It also improve the machinability of alloys by increasing matrix hardness. However, copper reduces the corrosion resistance and the ductility. The following diagram illustrates the maximum solubility of copper in aluminum (up to 6.5%) (2). Fig (4): Partial phase diagram for the aluminum-copper system showing the maximum solubility of copper in aluminum Good solubility of copper in aluminum up to 5.65% at T=548oC (eutectic temperature). Eutectic phase consists of ÃŽÂ ± phase (Al 5.65%Cu) which is ductile and ÃŽÂ ¸ phase (CuAl2;52.75%Cu) which is brittle. 5 > 5% Cu ÃŽÂ ± phase in some cases surrounded by ÃŽÂ ¸ phase. 33% Cu so brittle according to high amount of brittle ÃŽÂ ¸ phase. Aluminum-copper alloys are the group of aluminum alloys which are heat-treatable. Where by increasing temperature copper demonstrates increasing solid solubility in aluminum. As sequence significant additional strengthening could be produced and stabilizing of the structure could be achieved (7). References: 1. Rana R S, Purohit R, Das S. Reviews on the Influences of Alloying Elements on the Microstructure and Mechanical Properties of Aluminium Alloys and Aluminium Alloys composites. International Journal of Scientific and Research Publications, Volume 2, Issue 6, 2012; ISSN 2250-3153. 2. Substances Technologies. Wrought aluminum-copper alloys (2xxx). Weblog. Available from: http://www.substech.com/dokuwiki/doku.php?id=wrought_aluminum-copper_alloys_2xxx 3. Yong Lee C, Hyun Choi D, Bae Lee W, Park SK, Yeon YM, Jung SB. Microstructures and Mechanical Properties of Double-Friction Stir Welded 2219 Al Alloy. Materials Transactions , Vol. 49, No. 4 (2008) pp. 885 to 888. 4. Robinson J. S,. Cudd R. L,. Evans J. T. Creep resistant aluminium alloys and their applications. Materials perspective 2003. 5. The Aluminum Association, Inc. Aluminum Alloy Selection and Applications. 1998; (202) 862-5100. 6. ASM Vol 06 Welding, Brazing, and Soldering. 7. AlcoTec. The Differences Between Heat-Treatable and Non-Heat-Treatable Aluminum Alloys. Weblog. Available from: http://www.alcotec.com/us/en/education/knowledge/qa/The-Differences-Between-Heat-Treatable-and-Non-Heat-Treatable-Aluminum-Alloys.cfm 8. Yong Lee1C, Choi1DH, Lee WB, Park SK, Yeon YM, Jung SB. Microstructures and Mechanical Properties of Double-Friction Stir Welded 2219 Al Alloy. 2008;Materials Transactions, Vol. 49, No. 4 (2008) pp. 885 to 888.

Green Computing Research Essay

Operations, Natalie, is the program sponsor. Ito is the program manager, and there is a steering committee made up of ten senior executives, including Natalie, overseeing the program. There are several projects underneath this program, one being the Green Computing Research Project. The CIO and project sponsor, Ben, has given this project high priority and plans to hold special interview s to hand – pick the project manager and team. Ben is also a member of the program steer ing committee. Before coming to We A re Big, Inc., Ben sponsored a project at a large computer firm to improve data centerefficiency. This project, however, is much broader than that one was. The main purpose of the Green Computing Research Project is to research possible applications of gre en computing including: Data center and overall energy efficiency The disposal of electronic waste and recycling Telecommuting Virtualization of server resources Thin client solutions Use of open source software, and Development of new software to addres s green computing for internal use and potential sale to other organizations The budget for the project was $500, 000, and the goal was to provide an extensive report, including detailed financial analysis and recommendations on what green computing technologies to implement. Official project request forms for the recommended solutions would also be created as part of the project. Ben decided to have a small group of people, five to be exact, dedicated to working on this six – month project full – time and to call on people inoth er areason an as – needed basis. He wanted to personally be involved in selecting the proje ct manager and have that person help him to select the rest of the project team. Ben wanted to find people already working inside the company, but he was also open to reviewing applications for potential new employees to work specifically on this project as long asthey could start quickly. Since many good people were located in different parts of the world, Ben thought it made sense to select the best people he could find and allow them to wor k virtually on the project. Ben also wanted the project manager to do more than just mana ge the project. He or she would also do some of the research, writing, editing, and the like required to produce the desi red results. He was also open to paying expert consultants for their advice and purchasing books and related articles, as needed. Tasks 1. Research green computing and projects that have been done or are being done by large organizations such as IBM, Dell, H P, and Google. See www.greener – computing.com and similar sites provided on the companion Web site or that you find yourself. Include your definition of green computing to include all of the topics listed in the background scenario. Describe each of these areas of

Frederick Douglass Quotes on Womens Rights

Frederick Douglass was an American abolitionist and former slave, and one of the most famous 19th-century orators and lecturers. He was present at the Seneca Falls Womens Rights Convention of 1848 and advocated for womens rights along with abolition and the rights of African Americans. Douglass last speech was to the National Council of Women in 1895; he died of a heart attack suffered the evening of the speech. Selected Frederick Douglass Quotations [Masthead of his newspaper, North Star, founded 1847] Right is of no sex - Truth is of no color - God is the Father of us all, and we are all Brethren. When the true history of the antislavery cause shall be written, women will occupy a large space in its pages, for the cause of the slave has been peculiarly womans cause. [Life and Times of Frederick Douglass,1881] Observing womans agency, devotion and efficiency in pleading the cause of the slave, gratitude for this high service early moved me to give favorable attention to the subject of what is called womans rights and caused me to be denominated a womans rights man. I am glad to say I have never been ashamed to be thus designated. [Life and Times of Frederick Douglass,1881] [A] woman should have every honorable motive to exertion which is enjoyed by man, to the full extent of her capacities and endowments. The case is too plain for argument. Nature has given woman the same powers, and subjected her to the same earth, breathes the same air, subsists on the same food, physical, moral, mental and spiritual. She has, therefore, an equal right with man, in all efforts to obtain and maintain a perfect existence. Woman should have justice as well as praise, and if she is to dispense with either, she can better afford to part with the latter than the former. Woman, however, like the colored man, will never be taken by her brother and lifted to a position. What she desires, she must fight for. We hold woman to be justly entitled to all we claim for man. We go farther, and express our conviction that all political rights which it is expedient for man to exercise, it is equally so for women. [At the 1848 Womens Rights Convention at Seneca Falls, according to Stanton et al in [History of Woman Suffrage] A discussion of the rights of animals would be regarded with far more complacency by many of what are called the wise and the good of our land, than would be a discussion of the rights of woman. [From an 1848 article in the North Star about the Seneca Falls Womens Rights Convention and its reception by the general public] Should the females of New York be placed on a level of equality with males before the law? If so, let us petition for this impartial justice for women. In order to insure this equal justice should the females of New York, like the males, have a voice in appointing the law makers and the law administrators? If so, let us petition for Womans Right to Suffrage. [1853] On putting a priority, after the Civil War, on votes for African Americans males before women in general] When women, because they are women, are dragged from their homes and hung upon lampposts; when their children are torn from their arms and their brains dashed upon the pavement;... then they will have the urgency to obtain the ballot. When I ran away from slavery, it was for myself; when I advocated emancipation, it was for my people; but when I stood up for the rights of women, self was out of the question, and I found a little nobility in the act. [About Harriet Tubman] Much that you have done would seem improbable to those who do not know you as I know you. Quote collection assembled by Jone Johnson Lewis.

The Role of Woman - 1397 Words

Throughout the course of the semester I feel as thought the roles of women from the readings we have read all relate to each other. I don’t think that the roles of women in British and colonial society changed much, if not at all. Each reading that we have read, the women’s role is mainly to stay home with her children to raise them and tend to them while the husband works and makes the income while sheltering his family. Another role that the women throughout these time periods is that most of them don’t know the outside world because of not doing much but raising their children. A role of women throughout British and colonial society is that the pressure of society influences on them. The only role of women that changed throughout these periods was their freedom and privileges. During the Victorian Age, the â€Å"Angel in the House† displayed the roles of women in British and colonial society. The Angel in the House was your ideal women and a part of the upper class in society. This woman was educated, as she would teach her children how to read. The Angel in the House was very devoted to her husband, but most of the time she was relatively unhappy. Two readings that talk about the roles of the women, is the â€Å"Angel in the House† is the poem â€Å"Angel in the House† by Patmore and the reading â€Å"Of Queens’ Garden† by Ruskin. The poem is about Patmore and how he sets up a model of his wife insisting that that’s how women should be. This woman is held up to many expectations and as aShow MoreRelatedThe Role Of A Woman Essay1506 Words   |  7 PagesFor years, all things involving power and prestige had been controlled and owned by men. The role of a woman was believed to be limited to domestic responsibilities until the onset of the feminist movement. The twentieth century became a time of social change for women that found a voice in art via paintings, portraits, and photography. 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