退火诱导亚稳态Fe80Cu20合金固溶体的结构相变

利用扩展x射线吸收精细结构和x射线衍射研究了机械合金化制备的体心立方(bcc)的亚稳态Fe₈₀Cu₂₀合金固溶体的结构随退火温度的变化特点.结果表明，在300—873 K温度范围内，随着退火温度的升高，bcc结构物相的晶格常数近于线性降低，这主要是由于Cu原子从bcc结构Fe₈₀Cu₂₀合金固溶体中逐渐偏析出来，生成面心立方(fcc)结构的Cu物相所致.经603K退火后，Cu原子的平均键长R_Cu—Cu增加了0.003 nm左右，大约有50%的Cu原子从bcc结构的Fe₈₀Cu₂₀合金固溶体中偏析出来.在773 K退火后，bcc结构Fe_８０Cu₂₀合金固溶体近于完全相分离，生成了bcc结构的α-Fe与fcc结构的Cu物相. 关键词： 扩展x射线吸收精细结构 x射线衍射 ８０Cu₂₀合金')" href="#">Fe_８０Cu₂₀合金 机械合金化

Structural transition of Fe80Cu20 alloy induced by annealing

The extended x-ray absorption fine structure (EXAFS) and x-ray diffraction (XRD) techniques have been used to study the dependence of structural changes on annealing temperature for metastable body centered cubic (bcc) Fe₈₀Cu₂₀ alloy synthesized by mechanical alloying. In the temperature range from 300 to 873 K, the lattice constant of the bcc-structured phase exhibits a nearly linear decrease with the increase of annealing temperature. This is mainly due to the segregation of Cu atoms from the bcc Fe₈₀Cu₂₀ alloy to form the face centered cubic (fcc) Cu phase. Annealing at 603 K results in an increase of the average Cu—Cu distance R_Cu—Cu by about 0.003 nm, and about 50% Cu atoms are segregated from the bcc Fe₈₀Cu₂₀ alloy. After annealing at 773K, two phases of bcc α-Fe and fcc-Cu are almost completely separated from the as-milled bcc Fe₈₀Cu₂₀ alloy.