SHAPE MEMORY ALLOYS (SMA)

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:

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

(… адрес интернет-странички с видеороликами…)

SHAPE MEMORY EFFECT

(00:26)

PRE-LISTENING

1. Do you know the following words:

“wire”, “ice”, “to heat”, “to cool”, “hot”, “flame”, “soft”, “deformable”?

WHILE-LISTENING

Watch the video and answer the following questions:

2. What is the wire made of?

3. Why is it called “smart”?

4. How many stages can you divide the process on the video into?

5. Complete the following sentences about each stage of the process on the video:

a) We __________ the wire with __________.

b) The wire __________ soft and easily __________ .

c) We heat the __________ with a __________ .

d) The __________ turns to its __________ shape.

<== попередня сторінка	\|	наступна сторінка ==>
SMART MATERIALS (2)	\|	POST-LISTENING

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