3.8 An alloy of copper and gold has the structure shown in Fig. 3.75. Calculate the composition of this unit cell. What is the lattice type this structure? Given that 24 carat gold is pure gold, what carat gold does this alloy represent? of Au Cu Fig 3.75 The structure of Cu,Au.

On the basis of these models, explain why diamond is a very hard substance and graphite (e.g. pencil ‘lead’) is very soft.

Is Aluminium is commonly deliberately alloyed with iron? Why ?

Which of these statements about alloys and intermetallic compoundsis false? (a) Bronze is an example of an alloy. (b) “Alloy”is just another word for “a chemical compound of fixedcomposition that is made of two or more metals.” (c) Intermetallicsare compounds of two or more metals that have a definitecomposition and are not considered alloys. (d) If you mixtwo metals together and, at the atomic level, they separate intotwo or more different compositional phases, you have createda heterogeneous alloy. (e) Alloys can be formed even if the atomsthat comprise them are rather different in size.