Alloys 1


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Alloys 1

  1. 1. ALLOYS
  2. 2. MEANING <ul><li>Contain more than one element. </li></ul><ul><li>Usually mixtures of metallic elements (two or more metals). </li></ul><ul><li>Made for certain purpose. </li></ul>
  3. 3. Example of alloy products. Body parts of a car Golden jewelleries Rims
  4. 4. Arrangement of atoms in Metals <ul><li>In pure metals, atoms are all of the same size . </li></ul><ul><li>They arranged in layers . </li></ul>When a force is being applied…. The layers can slide over each other easily. <ul><li>Thus, pure metal can easily change its shape. </li></ul><ul><li>They are said to be </li></ul><ul><li>Ductile as they can be drawn into long wires. </li></ul><ul><li>Malleable as they can be hammered to form any shapes. </li></ul>
  5. 5. Arrangement of atoms in alloys Pure metal A Pure metal B <ul><li>Alloys have more than one kind of atoms. </li></ul><ul><li>Different atoms have different sizes. </li></ul><ul><li>They are mixed when they are in molten state (liquid). </li></ul>
  6. 6. Arrangement of atoms in alloys Pure metal A Pure metal B
  7. 7. Arrangement of atoms in alloys <ul><li>When a force is applied…. </li></ul><ul><li>the layers of atom in an alloy cannot slide over each other easily. </li></ul><ul><li>The movement of atoms get jammed up . This make them difficult to move. </li></ul>Thus make an alloys not ductile and not malleable but harder and stronger than the original constituent metals.
  8. 8. <ul><li>Problem statement: </li></ul><ul><li>Are alloys harder than pure metals? </li></ul>Experiment 9.1
  9. 9. <ul><li>Hypothesis: </li></ul><ul><li>Bronze is harder than copper </li></ul>
  10. 10. Variables: <ul><li>Manipulated variable: </li></ul><ul><ul><li>Different type of materials. </li></ul></ul><ul><ul><li>(copper and bronze). </li></ul></ul><ul><li>Responding variable: </li></ul><ul><ul><li>Diameter of dent. </li></ul></ul><ul><li>Fixed variable: </li></ul><ul><ul><li>Diameter of steel ball bearing, height of the weight, mass of the weight. </li></ul></ul>
  11. 11. Procedure string meter ruler weight <ul><li>Use cellophane tape to stick a steel ball bearing onto the copper block. </li></ul>steel ball bearing block of alloy / metal <ul><li>Hang a weight at a height of 50 cm above the ball bearing. </li></ul><ul><li>Drop the weight so that it hits the ball bearing. </li></ul>Set up the apparatus as shown in Figure 1 below.
  12. 12. <ul><li>Measure the diameter of the dent on the copper block. </li></ul><ul><li>Repeat steps 1 to 4 twice on the other parts of the copper block in order to obtain the average value. </li></ul><ul><li>Repeat step 1 to 5, replacing the copper block with the bronze block. </li></ul><ul><li>Record the readings in a table. </li></ul>
  13. 13. Results 2.5 2.3 2.5 2.4 Brass 3.2 3.3 3.1 3.2 Copper Average 3 2 1 Diameter of dents (cm) Blocks
  14. 14. Conclusion <ul><li>Hypothesis accepted. </li></ul><ul><li>Bronze is harder than copper . </li></ul>
  15. 15. TEST YOUR UNDERSTANDING <ul><li>Answer these questions by clicking on the best correct answer. </li></ul>1. Alloys are materials that contain A. only an element. B. two elements only. C. more than one element D. hydrogen and carbon elements only.
  16. 16. 2. Steel is harder than pure iron. This is because the atoms of steel are … A. more difficult to compress. B. More compact. C. More difficult to slide over one another. D. Smaller but heavier.
  17. 17. 2. Which of these are the properties of alloys? A. Ductile. B. Malleable. C. Ductile and malleable. D. Not ductile and not malleable.
  18. 18. Sorry, try again. Click here to go to previous question.
  19. 19. Congratulations. You are correct. Click here to proceed
  20. 20. Congratulations. You are correct. Click here to proceed
  21. 21. Congratulations. You are correct. Click here to proceed
  22. 22. <ul><li>Please complete the report on the experiment today at home. </li></ul><ul><li>Next lesson will be: </li></ul><ul><li>The aim of producing alloys. </li></ul><ul><li>Experiment 9.2 </li></ul>