(a) Mention 3 methods to increase the tensile strength of steel. Explain each method in some detail illustrating your answers with diagrams as appropriate. (10 marks) (b) What is understood by unlimited solubility, limited solubility and no solubility? Explain the differences between them. (7 marks) (c) What is precipitation hardening/age hardening? How is it achieved? (4 marks) (d) Explain the reason why ceramics normally have a compressive strength that is much higher than the tensile strength. (4 marks)