Most pure metals are soft and corrode easily. Alloying combines metals with other metals or non-metals to improve their strength, hardness and resistance to corrosion.
Foreign atoms of different sizes prevent the layers of atoms from sliding, making alloys harder than pure metals.
Alloy is a mixture of several types of metals or a mixture of metal and non-metal by a certain percentage.
Alloying is the process of forming alloys to improve the properties of pure metals.
Pure metals consist of identical atoms packed in neat, uniform layers. When a force is exerted, these layers easily slide over each other, making pure metals relatively soft, malleable and easily deformed.
By adding foreign atoms of different sizes through alloying, the orderly rows are disrupted. These mismatched atoms anchor the layers in place, making it much harder for them to slide past one another. Consequently, alloys possess superior mechanical strength, increased hardness and enhanced resistance to corrosion compared with pure metals.
Atoms are of the same size and arranged orderly in layers. When a force is applied, the orderly layers of atoms slide over each other easily. This makes pure metals relatively soft and malleable or ductile.
Foreign atoms have different sizes compared with the pure metal atoms. These foreign atoms disrupt the orderly arrangement and make it difficult for the layers of atoms to slide over each other when force is applied. As a result, alloys are harder and stronger than their pure metal counterparts.
Composition alteration. The composition or percentage of the contents of each element in alloys can be altered based on its intended use.
Historical fact. The first alloy found was bronze, discovered hundreds of years back in the Bronze Age to make tools and weapons.
Two experiments compare hardness and resistance to corrosion.
To study the hardness of alloys compared to pure metals.
Alloy is harder than pure metal.
A 1 kg weight is hung 50 cm above a steel ball taped to a metal block and dropped. The diameter of the dent formed is measured with a ruler. The procedure is repeated twice on different surfaces to get an average diameter, then repeated using a bronze block.
Observation. Copper (pure metal) produces a larger dent diameter because its layers of atoms slide easily. Bronze (alloy) produces a smaller dent diameter because foreign tin atoms disrupt the copper layers, making it harder.
To study the resistance to corrosion of alloys as compared to pure metals.
Alloy is more resistant to corrosion than pure metal.
Precautionary measure. Rub both nails with sandpaper before conducting the experiment to clean their surfaces.
Observation. After one week, the iron nail in test tube P shows the presence of a brown layer (rust), whereas the steel nail in test tube Q does not rust or shows high resistance to corrosion.
From skyscrapers to Maglev trains, alloys support modern technology.
Used for constructing skyscrapers such as the Petronas Twin Towers due to its hardness and corrosion resistance.
Used for aeroplane bodies because it is light and strong.
Used for musical instruments such as saxophones because it is shiny and corrosion-resistant.
Several metal and non-metal elements exhibit superconducting properties at low temperatures.
Superconductor alloy is a material that conducts electricity at high efficiency without electrical resistance.
It resists magnetic fields, allowing a superconducting material to float when placed on a magnet.
Railway tracks of high-powered Maglev trains enable the train to move by floating, preventing friction between the track and the body of the train, allowing high-speed travel.
Superconductor alloys such as niobium-titanium and niobium-tin are used in the construction of Magnetic Resonance Imaging (MRI) machines.
Answer in your mind, then press “Check Answer”.
What are the components of bronze and why is bronze harder than pure copper?
State two main advantages of using duralumin to build aeroplane bodies.
Name two superconductor alloys used in Magnetic Resonance Imaging (MRI) machines and state the special electrical property of superconductors.
Pure metals are stronger and harder than alloys because they are “100% pure”.
Pure metals are actually softer because their identical atoms form uniform layers that easily slip over each other under force. Adding foreign atoms makes an alloy harder by blocking layer displacement.
Alloying only involves mixing two or more different metals.
An alloy can also be a mixture of a metal and a non-metal, such as steel, which is a mixture of iron (metal) and carbon (non-metal).
1 Which of the following alloys is composed of copper and zinc?
2 Why is bronze harder than a pure copper block in Experiment 9.1?
3 Superconductor alloys such as niobium-titanium and are used in Magnetic Resonance Imaging (MRI) machines.
4 In Experiment 9.1, the metal block that produces a smaller average dent diameter is .
Drag each alloy to the correct description. On a phone, tap an answer first, then tap a matching box. Tap the Answer Choices area to return a selected item.
Write the correct alloy next to each description.
Answer choices: Steel • Pewter • Duralumin • Brass
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