Why is fcc softer than bcc

Additionally, cubic lattice structures allow slippage to occur more easily than non-cubic lattices. This is because their symmetry provides closely packed planes in several directions. A face-centered cubic crystal structure will exhibit more ductility deform more readily under load before breaking than a body-centered cubic structure. The bcc lattice, although cubic, is not closely packed and forms strong metals. Alpha-iron and tungsten have the bcc form. The fcc lattice is both cubic and closely packed and forms more ductile materials.

Gamma-iron, silver, gold, and lead have fcc structures. Finally, HCP lattices are closely packed, but not cubic. HCP metals like cobalt and zinc are not as ductile as the fcc metals. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. For example, cobalt and iron can both be FCC when heavily alloyed, especially with nickel.

You also know many common materials that take each form. I hope you can find many other useful articles on this website. Here is this list, in recommended reading order:.

If you are interested in more details about any specific crystal structure, I have written individual articles about simple crystal structures which correspond to each of the 14 Bravais lattices:. Simple Cubic 2. Face-Centered Cubic 2a. Diamond Cubic 3. Body-Centered Cubic 4. Simple Hexagonal 4a. Hexagonal Close-Packed 4b.

Double Hexagonal Close-Packed La-type 5. Rhombohedral 5a. Rhombohedral Close-Packed Sm-type 6. Simple Tetragonal 7. Body-Centered Tetragonal 7a. Diamond Tetragonal White Tin 8.

Simple Orthorhombic 9. This is very different from ionic or covalent bonds, where electrons are held by one or two atoms. The metallic bond is therefore strong and uniform. Since electrons are attracted to many atoms, they have considerable mobility that allows for the good heat and electrical conductivity seen in metals. Above their melting point, metals are liquids, and their atoms are randomly arranged and relatively free to move.

However, when cooled below their melting point, metals rearrange to form ordered, crystalline structures. Figure 2: Arrangement of atoms in a liquid and a solid. Crystals To form the strongest metallic bonds, metals are packed together as closely as possible. Several packing arrangements are possible. Instead of atoms, imagine marbles that need to be packed in a box.

The marbles would be placed on the bottom of the box in neat orderly rows and then a second layer begun. The second layer of marbles cannot be placed directly on top of the other marbles and so the rows of marbles in this layer move into the spaces between marbles in the first layer.

The first layer of marbles can be designated as A and the second layer as B giving the two layers a designation of AB. Notice that layer B spheres fit in the holes in the A layer. Packing marbles in the third layer requires a decision. Brass with high beta BCC content has excellent hot working properties, allowing it to be extruded into complex shapes and hot forges easily.

Category: science chemistry. Yes the APF is important, the atomic packing factor, that is the reason FCC has more slip systems, because of the way the atoms are arranged in the crystal. HCP metals are the most brittle. What is the structure of BCC? Table 1: Crystal Structure for some Metals at room temperature.

What is fcc structure? What is hcp structure? What is CCP lattice? What is a for BCC? Is BCC a primitive cell?