alloying

Rare earth reinforcement in the aluminum powder alloy, mainly fine grain strengthening, solid solution strengthening limited and rare earth compound second phase strengthening, etc. When not at the same time, for the amount of rare earths in rare earth aluminium alloy mainly exists in three forms: alpha (Al) solid solution in the matrix; Partial gathered in the grain boundary phase boundary, grain boundary and branches; Solid solution, or in the form of compounds in the compound. When rare earth content is low (less than 0.1%), rare earth mainly used two forms of distribution. The first form have the effect of the limited solid solution strengthening, the second type increases the resistance to deformation, promote the dislocation multiplication, the strength Calcium silicon. After joining the rare earths, the alloy as-cast organization, alloy grain size significantly reduced, could reduce the secondary dendrite spacing, rare earths and Al, Mg and Si element such as the formation of the intermetallic compound spherical and short rod distribution in grain boundaries or limits, distribution of a large number of dislocation in tissue. When the rare earth content is more than 0.1%, after a form began to dominate. At this time, rare earth with the other elements in the alloy begin to form many new phase containing rare earth elements; At the same time make change shape, size of the second phase, may make the second phase from a long strip shape into a short rod-shaped particles, such as, the size of the particles is also becoming more small, and scattered. Most containing rare earth elements in the second phase of the characteristics of the particles, the spheroidizing and refinement, this kind of change are reinforced aluminum alloy to some extent.