Question

Speculate the differences in properties between an HCP and an FCC material.

Please indicate the physical, electrical, Chemical, Optical and mechanical properties that differentiate the two crystal structures.

Answer 1

Answer:

                                    HCP                                                         FCC

Atoms in unit cell             6                                                      4        

Coordination number         12                                                12            

a/r ratio                            2                                                       2.82                                                

Stacking sequence       ABABAB                            ABCABCABC                                          

Metal                           Mg,Zn,Co                           Al,Cu,Pb                                

Important point:

1. Ductility of  FCC compound is high as compare to HCP. It means that HCP metal is more brittle as compare to FCC metal.

2. FCC component is more electro negative as compare to HCP.