"Metals and Alloys" Metal PPT Courseware 2

"Metals and Alloys" Metal PPT Courseware 2

learning target

1. Understand common metal materials

2. Understand the meaning and properties of alloys

3. Master several common alloys

Platinum has good ductility and can be drawn into filaments with a diameter of only 1/5000�;

Gold has good malleability and can be pressed into sheets with a thickness of only 1/10000�;

The unique yellow color of gold symbolizes wealth and nobility, and is widely used in jewelry.

Tungsten has a high melting point and can be used as filament;

Silver has good conductivity and is widely used in electronic manufacturing (such as printed circuits for computers, televisions, etc.);

An alloy is a substance with metallic properties formed by the fusion of one metal with other metals (or non-metals).

For example: The earliest bronze used in human history was an alloy formed from copper, tin and other elements.

The most common and widely used steel in the world is an alloy formed of iron, carbon and other elements.

Alloy properties:

1. High hardness

2. The melting point is generally lower than that of the component metals.

3. Generally speaking, the properties of alloys are not the sum of the properties of each component. Alloys have good physical, chemical and mechanical properties.

4. The properties of the alloy can be adjusted by the type and content of the added alloy elements and the conditions for forming the alloy.

Thought questions:

1. Why are the properties of alloys so different from those of pure metals?

Structural comparison of metals and alloys:

Changed the regular layered structure of metal atoms

2. Why are the melting points of most alloys generally lower than those of the component metals?

In a pure metal, all atoms are the same size and arranged very regularly. The atoms in the alloy vary in size and are not arranged as neatly as in pure metals, which reduces the interaction between atoms. Therefore, the melting point of most alloys is generally lower than that of the component metals.

Learning and Questioning:

Stainless steel commonly used in daily life has strong corrosion resistance in the atmosphere, but will be corroded in seawater. What's your inspiration for this?

Inspiration:

1. Stainless steel commonly used in daily life is relatively stable in the atmosphere and does not rust easily. However, if placed in seawater, the chlorine ions in the seawater will cause corrosion of this stainless steel.

2. The "stainlessness" of stainless steel is relative and related to the conditions of use.

Thinking and communicating:

1. What properties should the alloy used to mint coins have? Why?

Answer: The alloy used to cast coins should have a certain hardness and be resistant to wear and corrosion, so that the coins can be used for a certain period of time; the alloy used to cast coins should not be too hard, otherwise, the patterns and numbers on the coins will not be easily imprinted; The alloys used to mint coins cannot be too expensive, etc.

2. What conclusion can you draw from the different materials of 1 yuan, 50 cents and 1 dime coins?

Answer: The values ​​of the three metals: nickel>copper>aluminum.

3. Do you think the actual value of the alloy used to mint coins is less than the face value, equal to the face value, or higher than the face value? What might one do if it's above face value?

Answer: The actual value of the alloy used to mint a coin should be less than the face value. If it is above face value, people may collect the coin or sell it at a high price without using it as currency.

practice

1. Which statement about alloy is incorrect ( )

A. The melting point of the alloy is lower than the melting points of its component metals.

B. The hardness and strength of alloys are generally higher than those of pure metals

C. Alloy must be a substance formed by fusion of metals

D. Duraluminum, brass and steel are all alloys

Analysis: Alloys are not necessarily formed by the fusion of metals. For example, ferroalloys are formed by the fusion of iron and carbon.

2. The important materials used in the aircraft manufacturing industry are ( )

A. Mg-Al alloy

B. Cu-Sn alloy

C. Al-Si alloy

D. Stainless steel

3. Which of the following statements about magnesium-aluminum alloys is correct ( )

A. The melting point is higher than that of magnesium and aluminum.

B. The melting point is lower than that of magnesium and aluminum.

C. Harder than magnesium and aluminum

D. Harder than magnesium and aluminum

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For more information about the "Metals, Metals and Alloys" PPT courseware, please click on the Metal ppt Metals and Alloys ppt tab.

"Metals and Alloys" Metal PPT courseware:

"Metals and Alloys" Metal PPT courseware learning objectives 1. Understand the physical properties of metals, and know the relationship between the properties and uses of substances 2. Understand the concepts of metal materials and alloys; understand alloys and their characteristics, and know several common alloys 3. Feel the metal materials and people...