MA法制备Fe_(83)Nb_7B_9Cu_1纳米晶粉末及其热稳定性

Preparation of nanocrystalline Fe_(83)Nb_7B_9Cu_1 powders by mechanical alloying and their thermal stability

利用高能球磨法在Fe Nb B Cu体系中获得纳米晶粉末 ,研究了机械球磨过程中产物的组织结构、α Fe相平均晶粒尺寸及其热稳定性。结果表明 :采用Fe 2 0B中间合金粉末代替B粉并未明显影响机械合金化动力学过程 ;球磨至 5h时 ,即可获得平均晶粒尺寸约 18nm的α Fe单相过饱和固溶体 ,其后延长球磨时间 ,晶粒尺寸缓慢减小 ,至 45h后 ,平均晶粒尺寸减小到 9nm。退火处理后的XRD分析表明 ,α Fe过饱和固溶体从 10 0℃开始发生结构弛豫现象 ,738.8℃后则发生了相转变 :α Fe过饱和固溶体→α Fe固溶体 +Fe3 B +FeB ,在 5 5 0℃以内退火 ,纳米晶粒长大不明显 ,在 770～ 95 0℃范围内退火 ,晶粒开始明显长大 ,但晶粒尺寸仍处于纳米级范围。

Nanocrystalline powder in Fe-Nb-B-Cu system was obtained by high-energy ball milling. The average grain size, thermal stability of α-Fe phase in the powder were studied by XRD, DSC and SEM. The results show that replacing pure boron powder with Fe-20B master alloy does not affect the dynamic process of mechanical alloying. During the course of ball milling, α-Fe supersaturation solid solution, with an average grain size of 18 nm, can be obtained after 5 h of ball milling. Then with prolonging time of ball milling, grain size decreases slowly. The average grain size gets to 9 nm after 45 h of ball milling. The α-Fe solid solution undergoes structure relaxation from 100 ℃, and undergoes phase transformation from 738.8 ℃. The transition from α-Fe supersaturation solid solution to α-Fe solid solution, Fe 3B, and FeB gets the exothermic peak at 803.6 ℃. Annealing at temperature below 550 ℃, the nanocrystalline has no significant grain growth. Annealing at the temperature between 770 ℃ and 950 ℃, the grain of nanocrystalline grows obviously, but its grain size is still at nanometer range.