斷裂韌性的影響
( 1. 西安交通大學(xué) 金屬材料強度國家重點實驗室, 西安 710049；
2. 太原理工大學(xué) 表面工程研究所, 太原 030024)
摘 要: 應(yīng)用低能離子束輔助磁控濺射技術(shù)（IBAMS）沉積CrN薄膜， 用場發(fā)射掃描電鏡（FESEM）、原子力顯微鏡（AFM）和X射線衍射表征薄膜的組織結(jié)構(gòu)， 討論了轟擊能量對CrN薄膜組織、 晶粒度以及硬度和斷裂韌性的影響。 結(jié)果表明： 隨離子束輔助轟擊能量的升高， Cr-N薄膜由粗大的柱狀晶變?yōu)榧?xì)小的晶粒， 當(dāng)轟擊能量達(dá)到1 200 V時，薄膜呈現(xiàn)等軸晶結(jié)構(gòu)， 薄膜致密度增加。 FESEM得到的表面顆粒尺寸和AFM得到的粗糙度隨轟擊能量升高呈現(xiàn)相同的變化趨勢，這些表觀大顆粒是由許多小的亞晶塊聚集而成。 進(jìn)一步用X射線衍射譜形分析表明： 隨轟擊能量從0 V升高到800 V時， 亞晶塊的尺寸逐漸減小； 到800 V時， 晶塊尺寸約為9 nm， 但當(dāng)能量升到1 200 V時， 晶塊尺寸反而增大， 這是由離子束輔助轟擊導(dǎo)致的兩種不同機制而引起的， 一種是離子轟擊導(dǎo)致的噴丸碎化作用，而另一種為熱效應(yīng)引起的晶粒長大； 當(dāng)轟擊能量從0 V增加800 V時，薄膜的硬度和斷裂韌性都顯著提高， 與晶粒度的減小有關(guān)； 而到1 200 V時， 晶粒度較未輔助略大， 但卻具有很高的硬度以及較高的斷裂韌性，說明硬度和斷裂韌性的提高還與離子束轟擊導(dǎo)致薄膜的致密化增加有關(guān)。
關(guān)鍵字: 離子轟擊； 晶粒度； 硬度； 斷裂韌性
TANG Bin2， HE Jia-wen1
（ 1. State Key Laboratory for Mechanical Behaviour of Materials，
Xi'an Jiaotong University， Xi'an 710049， China；
2. Research Institute of Surface Engineering，
Taiyuan University of Technology， Taiyuan 030024， China）
Abstract: Cr-N films were deposited by low energy ion assisted magnetron sputtering (IBAMS). The microstructure was characterized by FESEM, AFM and XRD analysis. The effects of ion bombardment energy on microstructure, grain size, hardness and fracture toughness of Cr-N films were studied. The results show that, with the increase of ion energy, the Cr-N film changes from large columnar structure to fine dense grains. When the assisted ion energy reaches 1 200 V, the structure changes to equiaxial and the film density increases. The aggregation observed by FESEM and roughness by AFM change with the bombarding ion energy increasing in similar trend. However, the aggregate particles compose of many small sub-grains, which are analyzed by X-ray diffractrometry. The sub-grain size decreases when the bombarding ion energy increases from 0 to 800 V and reaches about 9 nm at 800 V. However, it increases again at 1 200 V. The results suggest that two different mechanisms take place during ion bombardment. One is peening effect which results in grain refining and the other is thermal effect leading to grain growth. Both the hardness and fracture toughness increase with the energy increasing from 0 to 800 V, which could relate to the decrease of grain size. The grain size at energy of 1 200 V closes to that of 0 V, but the hardness and fracture toughness is higher than that of 0 V. It suggests that the improvement of hardness and fracture toughness relates to the densification of the film deposited by ion bombardment.
Key words: ion bombardment； grain size； hardness； fracture toughness
