Plastic deformation crystal symmetry

Plastic deformation is more difficult in intermetallics than in metals and conventional metals alloys because of the stronger atomic bonding and the resulting ordered atomic distribution, which gives rise to more complex crystal structures (Paufler, 1985). Experience indeed shows that the brittleness of intermetallics increases with decreasing lattice symmetry and increasing... 

Therefore lattice structures with closely packed planes allow more plastic deformation than those that are not closely packed. Also, cubic lattice structures allow slippage to occur more easily than non-cubic lattices. This is because of their symmetry which provides closely packed planes in several directions. Most metals are made of the body-centered cubic (BCC), face-centered cubic (FCC), or hexagonal close-packed (HCP) crystals, discussed in more detail in the Module 1,... 

The mechanical properties of Pu metal are highly variable because of the dominant influences of structure and deformation mechanism, which can be significantly altered by thermal and mechanical treatments. The a, and y forms of Pu, having crystal structures with low symmetry, are hard and strong, and lack ductility. When the mechanism for plastic deformation is restricted to slip, ductility is poor because the extent of slip is very limited in these polymorphic... 

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