XAFS和XRD研究高能球磨对Fe_(70)Cu_(30)合金结构的影响  

X-ray absorption fine structure and x-ray diffraction studies on structures of Fe_(70)Cu_(30) alloys affected by mechanical alloying

作　　者：范江玮[1] 卞清[2] 殷士龙[3] 闫文盛[1] 刘文汉[4] 韦世强[1] 

机构地区：[1]中国科学技术大学国家同步辐射实验室,合肥230029 [2]中国人民解放军理工大学理学院,南京210016 [3]河海大学数理系,南京210024 [4]中国科学技术大学物理系,合肥230026

出　　处：《物理学报》2004年第2期514-520,共7页Acta Physica Sinica

基　　金：中国科学技术大学一流大学建设重点项目资助的课题~~

摘　　要：利用XRD和XAFS方法研究机械合金化Fe70 Cu30 二元金属合金随球磨时间的结构变化 .XRD结果表明 ,球磨 2h后 ,部分金属Fe与Cu生成Fe Cu合金 ;球磨 2 0h后 ,金属Fe与Cu已完全合金化生成Fe -Cu合金 ,并只在 2θ =4 4°处出现一个宽化的弱衍射峰 ,认为是在球磨 2 0h后的Fe70 Cu30 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颗粒的晶格产生较大的畸变 ,其无序度σ(σ =σT+σS)为 0 0 190nm .球磨 5h后 ,部分fcc结构的Cu原子进入了无序度相对较小的bcc结构的α -Fe相 ,导致Cu原子的平均无序度σ降为 0 0 10 8nm .球磨 10h后 ,样品中很大比例的Fe原子处于fcc结构的Fe -Cu合金相 ,其无序度为σ =0 0 119nm ;而大部分Cu原子依然保持fcc结构 ,无序度为σ =0 0 110nm .这是由于扩散到bcc结构α -Fe相的Cu原子超过某一浓度后 (约 30 %— 4 0 % ) ,Cu原子能诱导其产生fcc结构相变所致 .球磨时间增加到 2 0h ,样品中Cu原子和Fe原子在fcc和bcc相的比例与球磨 10h基本相同 ,生成的Fe -Cu合金混合相的组成和结构分别近似于bcc结构的Fe80 Cu2 0 和fcc结构的Fe6 0 Cu4 0 .The XAFS and XRD techniques were used to study the local structure changes around Fe and Cu atoms in the mechanical alloying (MA) Fe 70Cu 30 with the milling times. At the initial MA stage milling for 2 hours, the Cu fcc lattice in Fe 70Cu 30 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 Fe 70Cu 30 milled for 20 hours is similar to that of the Fe 70Cu 30 milled for 10 hours. The final MA product is composed of two phases: Fe 80Cu 20-like bcc structure and Fe 60Cu 40-like fcc structure.

关 键 词：铁铜合金 机械合金化 合金结构 X射线衍射分析 球磨时间 弱衍射峰 X射线吸收精细结构分析 

分 类 号：TG131[一般工业技术—材料科学与工程]