XAFS和XRD研究高能球磨对Fe70Cu30合金结构的影响

利用XRD和XAFS方法研究机械合金化Fe₇₀Cu₃₀二元金属合金随球磨时间的结构变化.XRD结果表明，球磨2 h后，部分金属Fe与Cu生成Fe-Cu合金；球磨20h后，金属Fe与Cu已完全合金化生成Fe-Cu合金，并只在2θ=44°处出现一个宽化的弱衍射峰，认为是在球磨20h后的Fe₇₀Cu₃₀合金中共存着fcc和bcc结构的Fe-Cu合金相.XAFS结果进一步表明，在球磨的初始阶段(2h)，fcc结构的Cu颗粒的晶关键词：XAFSXRD70Cu₃₀合金')" href="#">Fe₇₀Cu₃₀合金机械合金化

X-ray absorption fine structure and x-ray diffraction studies on structures of Fe70Cu30 alloys affected by mechanical alloying

The XAFS and XRD techniques were used to study the local structure changes around Fe and Cu atoms in the mechanical alloying (MA) Fe₇₀Cu₃₀ with the milling times. At the initial MA stage milling for 2 hours, the Cu fcc lattice in Fe₇₀Cu₃₀ mixture is largely distorted, and the disorder factor σ(σ=σ_T+σ_S) of Cu atoms is about 0.0190 nm. After being milled for 5 hours, part of the Cu atoms located at the grain boundaries diffuses into the bcc lattice of the α-Fe phase, which makes the average disorder factor σ around Cu atoms decrease to 0.0108 nm. When the milling time reaches 10 hours, most of the Fe atoms are in the fcc Fe-Cu phase whose disorder factor σ is about 0.0119 nm, while the local structures of Cu atoms mainly maintain fcc structure, and the σ around the Cu atoms is about 0.0110 nm. We consider that the bcc structural Fe-Cu phase might be induced into the fcc structure by Cu atoms, when the concentration of Cu atoms incorporated into the bcc Fe-Cu phase is increased to about 30%—40%. The XAFS result of the Fe₇₀Cu₃₀ milled for 20 hours is similar to that of the Fe₇₀Cu₃₀ milled for 10 hours. The final MA product is composed of two phases: Fe₈₀Cu₂₀-like bcc structure and Fe₆₀Cu₄₀-like fcc structure.