Solve Question 7,8,9,10,11 and 12

7- What are the main mechanisms of solidifications? 8- Mentions the types of solidification defects? 9. What is meant by "microstructure", indicate with the aid of drawing the different stages of the internal structure development formation from atomic to microstructure scale of metals. 10- An ASTM grain size determination is being made from a photomicrograph of a metal which has a magnification of 100X. What is the ASTM grain size number of the metal if there are 64 grains per square inch? 11- If there are 60 grains per square inch on a photomicrograph of a metal at 200 X, what is the ASTM grain size number of the metal? 12- Give and discuss two main strengthening mechanisms of single phase metals