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Explain any two of the following: (i) Crystalline and amorphous structures; (ii) Dendritic growth; (iii) A cooling curve for an alloy; (iv) Brittleness in crystal cells. - Leaving Cert Engineering - Question Question (a) - 2009
Question Question (a)
Explain any two of the following: (i) Crystalline and amorphous structures; (ii) Dendritic growth; (iii) A cooling curve for an alloy; (iv) Brittleness in crysta... show full transcript
Worked Solution & Example Answer:Explain any two of the following: (i) Crystalline and amorphous structures; (ii) Dendritic growth; (iii) A cooling curve for an alloy; (iv) Brittleness in crystal cells. - Leaving Cert Engineering - Question Question (a) - 2009
Step 1
Crystalline and amorphous structures
Answer
Crystalline structures are characterized by a highly ordered arrangement of atoms, which create a repeating pattern. Metals, like copper and iron, exhibit crystalline structures that are essential for their mechanical properties. In contrast, amorphous structures lack this long-range order, resulting in a more random arrangement of atoms. Common examples include glass and certain synthetic plastics, which have irregular atomic arrangements contributing to different physical attributes compared to crystalline materials.
Step 2
Dendritic growth
Answer
Dendritic growth refers to the process that occurs during solidification of metals. As a metal begins to cool, solidification starts at specific points, which grow outward in tree-like branches known as dendrites. These formations result from the movement of the liquid phase to solid as temperature decreases. Dendritic structures can affect the mechanical properties of the metal, influencing attributes such as strength and toughness.