shape memory alloys
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The three main types of shape memory alloys, the copper-zinc-aluminum-nickel-copper-aluminum-nickel and nickel-titanium (NiTi) alloys have been, but can the SMA by alloying zinc, copper Gold can be used, and iron. NiTi alloys are generally more expensive and the transformation of austenite to martensite on cooling, Mf is the temperature at which the transition to martensite on cooling is complete. Consequently, the heating and AF What are the temperature at which begins the transformation of austenite to martensite and ends. Repeated use of the shape memory effect can lead to a shift of the characteristic transformation temperatures (this effect is known as functional fatigue, because it is closely related to a change in the microstructure and functional properties of the material conditions).
The transition from martensite phase to austenite phase is only dependent on temperature and stress, no time, because most changes are gradual, because there is no diffusion involved. The austenite structure of the name of the steel alloy with a similar structure. It is the reversible diffusion-less transition between these two phases, which may lead to the special features. Although martensite of austenite are formed by rapid cooling, carbon steel, the process is not reversible, so any steel shape memory properties.
In this figure (T) represents the martensite. The difference between the transitional heating and cooling transition rise to the shape of the curve depends on the material properties of shape memory alloys, such as alloying and work hardening
One-way vs. two-way shape memory alloys
shape memory alloys have various Shape Memory effects. Two common side effects are one-way and two-way shape memory. A schematic representation of the effects is shown below.
In the above illustration, the procedures are very similar martensite (a) by a reversible deformation of the one-way effect or severe deformation with an irreversible amount for the two-way (b) heating the sample (c ) and cooling again (d).
One way memory effect
When a shape memory alloy is in its cold state (below), the metal can be bent or stretched and is heated until it forms above the critical temperature. When heated, it changes the shape of the original. If the metal cools again it will remain in the hot form, deform up again.
With the one-way effect, cooling from high temperatures does not change in a macroscopic form. A deformation is needed to low-temperature forms. On heating, transformation starts with As and Af is complete (usually 2 to 20 C or warmer, depending on the alloy or the loading conditions). What determines the nature and composition of the alloy. He can be varied between 150 C and 200 C

two-way memory effect, the two-way shape memory effect is the effect that the material is two different forms: one remembers at low temperatures and high temperature in the mold. A material that shows shape memory effect, but the heating and cooling and a two-way shape memory. This can be obtained even without applying an external force (intrinsic two-way effect). The reason that the material behaves so differently in these situations is in education. Training means that shape memory learning in a certain way to behave. Under normal circumstances, a shape-memory alloy “remembers” the high-temperature re-form, but when heated to high temperature form, immediately “forgets” the low-temperature form. However, it can be “trained” to “remember” a few memories of leaving the deformed state at low temperature in the high-temperature phases. There are several ways to do this. Shape, trained object is heated beyond a certain point lose the two way memory effect, this is called “amnesia” is known. Pseudo-elasticity />

This allows the metal to be bent twisted and pulled, before the reform of its form when it is released. This means that the frames of the shape memory alloy glasses is claimed, “virtually indestructible” because it takes no amount of bending to a permanent plastic deformation is shown.

The transition temperature of martensite start temperature shape memory alloys which they function depends on a number of factors including the alloy chemistry. Shape memory alloys with transformation temperatures in the range of 1960-1450 K have been made. Zarinejad and colleagues have recently shown that the martensite start temperature increases with the decrease of the valence electron density (concentration) of these alloys.

The story first reported steps towards the discovery of the shape memory effect in the 1930s was accepted. According to Otsuka and Wayman (1998), A. Lander of the pseudoelastic behavior of the Au-Cd alloy discovered in 1932. Greninger & Mooradian (1938) observed the emergence and disappearance of a martensitic phase by lowering and raising the temperature of a Cu-Zn alloy. The main phenomenon of the memory effect of the thermo-elastic behavior of the martensite phase is generally considered a decade later by Khan & Kurdjumov dross (1949) and were also reported by Chang & Read (1951).
The nickel-titanium alloys developed initially by the U. 19621963 S. Naval Ordnance Laboratory and commercialized under the trade name Nitinol (an acronym for Nickel Titanium Naval Ordnance Laboratories). Their remarkable properties were discovered by accident. An example that many times was examined in a laboratory management meeting presented. One of the staff technical director, Dr. David S. Muzzey decided to see what would happen if the sample was exposed to heat, and held his pipe lighter underneath. Surprisingly, the sample is returned to its original elongated shape.
There is another type of SMA, the so-called ferromagnetic shape memory alloys (FSMA), which changes shape under strong magnetic fields. These materials are particularly important because the magnetic response tends to be quicker and more efficient than the temperature induced reactions.
Metal alloys are not the only thermally responsive materials, shape memory polymers have been developed and became commercially available in the late 1990s.

Many crystal structures of metals have different crystal structures with the same composition, but most metals do not show the shape memory effect. The special feature of shape memory alloys which are provided in their original form after heating and again that their crystal structure transformation is fully reversible. In the majority of atoms are local transformations in the crystal structure of the metal by diffusion traveling, changing the composition, although the metal is produced as a whole with the same atoms. Reversible conversion is not this type diffusion of atoms, the atoms, but all were at the same time a new structure, much can be done in the way of a parallelogram to a square by two opposite sides. At different temperatures, different structures are preferred, and if the structure is cooled through the transition temperature, the martensitic structure is formed from the austenitic phase.

Manufacture shape memory alloys are generally produced by molding, by vacuum induction melting or arc melting equipment. These are special techniques used to remove impurities in the alloy to a minimum, and ensure that the metals are well mixed. The bar is then rolled into long pieces and then looked drawn into a wire twisting.
The way in which the alloys are “trained” depends on the properties. The “training”, dictated the shape, the alloy will be remembered as it is heated. This is done by heating the alloy, so the dislocations to restore order in stable positions, but not so hot that the material recrystallized. They are heated between 400 C and 500 C for 30 minutes. Typical variables for some alloys and 500 C for more than five minutes. You
is formed hot and quickly cooled by quenching in water or cooling air.

Features The copper-base and Ni-Ti (nickel and titanium)-based shape memory alloys are considered to be material. These compositions can take nearly any shape and size are produced.
The yield stress of shape memory alloys is lower than that of conventional steel, but some compositions have a higher yield than plastic or aluminum. Yield 500 MPa for Ni Ti distance. The high cost of the metal itself and the requirements of the application is difficult and expensive to implement in a design FGL. As a result of these materials in applications where the supply or the elastic properties of the type of memory effect can be exploited. The most common application is in operation.
One of the benefits of shape memory alloys is the high level of recoverable plastic strain that can be activated. The maximum recoverable elongation of these materials can not be kept in permanent damage, up 8% for some alloys. Compared with a maximum load of 0.5% for conventional steels.

Aircraft Industrial Applications See also:
Boeing Aircraft, General Electric Aircraft Engines, Goodrich Corporation, NASA, and All Nippon Airways developed the Variable Geometry Chevron shape memory alloys which reduce aircraft engine noise. View all new Boeing aircraft will be equipped with this new technology.

Also Piping: Piping
The first commercial application of the consumer for the shape memory material was as clutch pipes, for example, oil pipes for industrial applications, pipes and similar types of consumer / commercial applications . The late 1980s saw the commercial introduction of Nitinol as an enabling technology in a number of minimally invasive endovascular medical applications. Although more expensive than stainless steel, self-expanding properties of Nitinol alloys manufactured SDR (body Response), have an attractive alternative to balloon expandable devices. On average 50% of all peripheral vascular stents currently on the world are manufactured with nitinol.

Robotics See also: Robotics
Also, studies on the use of these materials in robotics (z. B. “robot wife Lara), because they allow for very small robots creation. Shortcomings of the technology are energy efficiency, slow response times and large hysteresis.
Nitinol are also used in robotics (eg, the robot walks, because the hobby) and a few magic tricks, especially in the heat and change shape.
medicine, optometry

include spectacle frames made of titanium shape memory alloys sold under the trademark TITAN flex and Flexon. These frames are usually of shape memory alloys, who in the expected transition temperature at room temperature. This provides the framework for large deflection under load carried, but once the desired shape, the metal is again unloaded. The apparently very large elastic strains are due to stress-induced martensitic effect, where the crystal structure may change under load, so as to temporarily change the shape under load. This means that products from shape memory alloys to withstand accidental damage.

Orthopaedic Surgery This section is in need of attention from an expert on the subject. WikiProject Medicine or the Medicine Portal may be able to recruit a school to help. (February 2009)
memory metal is used in orthopedic surgery for fixation of osteotomies, usually around the foot and ankle. The device, usually an important food crop, is stored in a refrigerator in its shape and is designed for drilling holes into the bone implanted for an osteotomy. As a staple food it warms back to the non-deformable state and compressed along the bony surfaces Union to promote the osteotomy.

has grown over the years, an important area of development for medicine. One example is the prevalence of dental braces SMA technology provide a permanent tooth-moving forces to the teeth, which was developed in 1972 by George Andreasen nitinol arch orthodontist. This revolution clinical orthodontics and has an effect on fiber development. Andreasen shape memory alloy has a patterned shrink and move within a certain temperature ranges because of its geometric programming.
Harmeet D. Walia later, the alloy for the production of root canal files used in endodontics.

Materials metal alloys with the memory effect at different temperatures and different percentages of the solid solution content.
Ag-CD 44/49.
% Cd Au-Cd 46.5/50 at. Cd%
Al Cu Ni 14/14.5 wt% Al and 3/4.5 wt% Ni-Sn-Cu
ca. At 15.
% Sn-Cu Zn 38.5/41.5 wt% Zn
Cu-Zn-X (X = Si, Al, Sn)
Fe-Pt-ca. At 25.
% Pt Mn-Cu 5 / 35 on.
Fe% Cu-Mn-Si-Pt alloys

Co-Ni-Al-Ni-Ga Co

Ni-Fe-Ga
Ti -Pd in various concentrations
Ni-Ti (~ 55% Ni) Ni-Mn-
Go

References ^ shape memory materials, K. Otsuka, CM Wayman, Cambridge University Press, 1998 http://catdir.loc.gov/catdir/samples/cam034/97036119.pdf,
^ martensitic transformation and shape memory effect in alloys and Ti50Ni10Au40 Ti50Au50, SK WU and CM Wayman, Metallography 20:359-376 (1987)
^ influence of work hardening and heat treatment on the substructure and deformation behavior of Tini Shape memory alloys, P and K FILTP Mazanec, Scripta Metallurgica et Materialia, Vol 32nd Nr. 9, pp. 1375-1380. 1995
^ http://www-personal.umich.edu/ ~ btrease / share / SMA Shape Training Tutorial.pdf
^ Kauffman, George and Isaac Mayo. “Memory Metal.” Chem Matters October 1993: 4-7.
^ Http: / / www.wolaa.org / files / Nitinol_Oral_History.pdf, Oral History by William J. Buehler
^ http://www.lararobot.
^ New York Times obituary for Dr. Andreasen

read Dürig, TW, Melton KN, and CM Wayman D Stckel. “Technical aspects of shape memory alloys. ISBN 0-7506-1009-3. London: Butterworth Heinemann, 1990.
K. and T. Shimizu Tadaki, Shape Memory Alloys, H. Funakubo, Ed., Gordon and Breach Science Publishers, 1987 External Links

Shape Memory Alloys and Their Applications – Introductory information on shape memory alloy Nitinol Technical Information
(Johnson Matthey, Inc.)
BBC report on the medical applications of Nitinol
SFB 459: A German Research Center for Shape Memory Alloys
SMAterial.com – phenomena, crystallography, modeling, simulation and applications of SMA – Do. POISON animations to demonstrate the effect.
Texas A & M University’s Shape Memory Alloy Research Team – SMA overview, publications, etc.
Institute of Physics, ASCR – Research projects, publications, events and conferences, functional materials
Berkeley – Bioeng / ME C117 Structural Aspects of Biomaterials – video lecture: Dr. Scott Robertson, Stents: Fatigue and Fracture, LBL – Material properties of Nitinol stents
Berkeley – Bioeng / ME C117 Structural Aspects of Biomaterials – Video Lecture: Dr. Alan Pelton, Stent Design, Nitinol Device Company (NDC) – Material properties of Nitinol stents

SMST Proceedings various patents and publications on shape memory alloys (German)
Category: Alloys | Smart Materials | MetallurgyHidden categories: technology Articles expert attention | Articles engineering expert attention | Articles need attention from experts in February 2009 | All articles need expert attention | Articles Medical Experts attention

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diabetes need to care for their feet (Alternative Medicine) to take
It was confirmed that the health of the diabetic foot is very important and any injury or bruising, the size cause of the problems a place right down to the bone and cause gangrene, so diabetics should pay attention to their feet from shoes to socks and nails on the heel. Experts told a press conference that for diabetics is the most vulnerable organ to their feet. The feet are the organs most exposed, so that when blood flow to the feet, he slowly start to lose sensitivity. One expert said that even a small dent left by the feet more susceptible to injury so they could keep diabetic feet:
should be protected, “Your feet should be washed dried every night with warm water and thoroughly wetted. After sports and hiking, Should the bottom of the feet are checked with a mirror to ensure that no pressure points. should not socks are too big or too small, should lead to crushed or broken. shoes are made of soft leather, with a smooth inside and not pointed or conical front. toenails should be cut short. The nails are cut just been completed. “(Alternative Medicine)
experts warn that if diabetics do not take these warnings seriously and do not follow these guidelines the on feet can lose or his feet, “the treatment is too difficult and long. If injury is not healed properly, even a little bruise the size of a body, the bone can be reached and gangrene and loss of toes or entire feet cause . Alternative

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diabetes These three types of diabetes are the same with some variations, each with Diabetes is a common, and that little or no ability to transfer glucose from the blood into the cells, which in the case of the primary fuel is converted. We all have glucose in the blood, if we do not have diabetes. Glucose is the main source of food we eat. When we eat, the digestive system breaks food into glucose, which is found in the blood in the small intestine.

Those who do not have diabetes at insulin
A family history of diabetes increases the risk for future generations.
diabetes can happen in a society of people, but it is most common among whites.
Half of type 1 diabetes under the age of 20 years. Are 20 years or younger increases the risk.
Most of the children whose parents have diabetes, not the disease, but scientists still believe that heredity an important role in type 1 diabetes is because it tends to run in families.
The researchers have increased to several genes, the risk of type 1 diabetes studied. But they have no single gene that causes diabetes.
type 1 diabetes has many characteristics of an auto-immune conditions. In autoimmune diseases, the immune system, protects them against the disease by killing invading germs. In the case of type 1 diabetes, the immune system kills the cells in the pancreas that produces insulin.
Approximately 95% of diabetes patients have Type 2 diabetes, also known as non-insulin-dependent diabetes mellitus or NIDDM. Type 2 diabetics produce insulin but the cells in their bodies’ insulin resistance, “they can not respond to the hormone, so glucose in the blood increased. Some people with type 2 diabetes inject insulin, but most of the disease a combination of weight loss, exercise, a prescription oral diabetes drug control and strict control.

risk
Similar to Type 1, Type 2 disease also results in families and increase the risk for future generations.
The majority of patients with type 2 over 30 years of age. Half of all new cases are between 55 years and older.
In a comparison between whites and Asians, Type 2 diabetes is more common in Native Americans, African Americans, Latinos found, and Hispanics.
insulin resistance leads to an increase in weight and reduction in physical activity. Most people suffering from diabetes mellitus type 2 are overweight and sedentary lifestyles, increases the weight by at least 20 percent more than the recommended weight, according to their height and build.
Less exercise, especially for those who Obesity , increased the risk for diabetes.
If a woman developed gestational diabetes during pregnancy has a higher risk of type 2 diabetes later.
Women who give birth to babies weighing 9 pounds or more have an increased risk for type 2 diabetes.

gestational diabetes only affects pregnant women with no history diabetes. Almost 137,000 American women develop gestational diabetes each year.

. But research shows that approximately 40% of women with gestational diabetes, type 2 diabetes face within 15 years. All pregnant women have gestational diabetes between their 24th and 28 week of pregnancy were examined.

gestational diabetes and insulin resistance may, by maintaining a healthy weight that healthy food and with the help regular physical activity to avoid.

risk
diabetes problem flows from generation to generation.
in weight gain, insulin resistance increases.
Native Americans, African Americans and people of Hispanic descent are at increased risk. Whites and Asians have a lower risk.

hormones may play an important role. Pregnant women produce various hormones essential for the growth of their babies. However, these hormones interfere with the rights of the mother’s ability of insulin in the body, causing insulin resistance.

Every pregnant woman has a certain degree of insulin resistance . But if this resistance is full gestational diabetes, usually appears around the 24th week of pregnancy. Therefore, all pregnant women are seen in the period of gestational diabetes.

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