Shape memory alloys (sma)

SMART MATERIALS (2)

Read the text and fill in the gaps. Use the words given in the box:

solid design alloys changed special shape technology properties type smart

Science and (1) __________ have made amazing developments in the (2) __________ of electronics and machinery using standard materials, which do not have particularly (3) __________ properties (i.e. steel, aluminum, gold). Imagine the range of possibilities, which exist for special materials that have properties scientists can manipulate. Some such materials have the ability to change (4) __________ or size simply by adding a little bit of heat, or to change from a liquid to a (5) __________ almost instantly when near a magnet. These materials are called (6) __________ materials.
Smart materials have one or more properties that can be changed. Most everyday materials have physical (7) __________, which cannot be significantly altered; for example if oil is heated it will become a little thinner, whereas a smart material with variable viscosity may turn from a fluid which flows easily to a solid. Different smart materials already exist, and are being researched extensively. These include piezoelectric materials, magneto-rheostatic materials, electro-rheostatic materials, and shape memory (8) __________. Some everyday items are already incorporating smart materials (coffee pots, cars, the International Space Station, eyeglasses) and the number of applications for them is growing steadily.
Each individual (9) __________ of smart material has a different property which can be significantly altered, such as viscosity, volume, and conductivity. The property that can be (10) __________ influences what types of applications the smart material can be used for.

Read the text and choose the best heading (A, B, C) to each part:

A. Applications of Shape Memory Alloys.

B. What are Shape Memory Alloys?

C. Advantages and Disadvantages of Shape Memory Alloys

I. _____________________________

Shape memory alloys (SMA's) are metals, which exhibit two very unique properties, pseudo-elasticity, and the shape memory effect. Arne Olander first observed these unusual properties in 1938, but not until the 1960's were any serious researches made in the field of shape memory alloys. The most effective and widely used alloys include NiTi (Nickel - Titanium), CuZnAl, and CuAlNi.

II. ____________________________

The unusual properties mentioned above are being applied to a wide variety of applications in a number of different fields. The shape memory effect is currently being implemented in:

• coffee pots
• the space shuttle
• thermostats
• hydraulic fittings (for airplanes)

Some examples of applications in which pseudo-elasticity is used are:

• eyeglass frames
• bra underwear
• medical tools
• cellular phone antennae
• orthodontic arches

III. ___________________________

Some of the main advantages of shape memory alloys include:

• bio-compatibility
• diverse fields of application
• good mechanical properties (strong, corrosion resistant)

There are still some difficulties with shape memory alloys that must be overcome before they can be used up to their full potential. These alloys are still relatively expensive to manufacture and machine compared to other materials such as steel and aluminium. Most SMA's have poor fatigue properties; this means that while under the same loading conditions (i.e. twisting, bending, compressing) a steel component may survive for more than one hundred times more cycles than a SMA-element.

Answer the following questions:

1. How many unique properties have the SMAs got?

2. What are they?

3. How long is the history of SMAs?

4. What are the most famous alloys?

5. What property of SMAs is mostly used in Medicine?

6. What are the advantages of the SMAs?

7. What are the disadvantages of the SMAs?

Part III

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