李銳陽(yáng),袁子洲,康 健,張香云
(蘭州理工大學(xué) 甘肅省有色金屬先進(jìn)加工與再利用省部共建國(guó)家重點(diǎn)實(shí)驗(yàn)室, 蘭州 710050)
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Y元素的添加對(duì)Zr56Co28Al16非晶合金在模擬體液中耐蝕性能的影響*
李銳陽(yáng),袁子洲,康健,張香云
(蘭州理工大學(xué) 甘肅省有色金屬先進(jìn)加工與再利用省部共建國(guó)家重點(diǎn)實(shí)驗(yàn)室, 蘭州 710050)
摘要:采用銅模吸鑄法制備了(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)非晶合金,研究了(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)非晶合金在模擬體液(PBS溶液)中的耐蝕性。運(yùn)用X射線衍射(XRD)表征試樣的結(jié)構(gòu),運(yùn)用電化學(xué)工作站、場(chǎng)發(fā)射掃描電鏡(SEM)和X射線光電子能譜(XPS)研究Y元素的添加對(duì)Zr56Co28Al16非晶合金耐蝕性的影響。結(jié)果表明,適量Y元素的添加顯著提高了Zr56Co28Al16非晶合金的耐蝕性,但過(guò)量Y元素的添加,在非晶基體上有晶體相的析出,降低了Zr56Co28Al16的耐蝕性能。
關(guān)鍵詞:Zr基非晶合金;Y元素;模擬體液;耐蝕性能
1引言
Zr基非晶合金具有良好的非晶形成能力、高比強(qiáng)度、低彈性模量、良好的抗磨損性能等優(yōu)點(diǎn),而成為非晶界的研究熱點(diǎn)[1]。同時(shí),非晶是單向無(wú)定形結(jié)構(gòu),不存在類似晶體中晶界、位錯(cuò)等缺陷,而具有良好的抗腐蝕能力,使得Zr基非晶合金在生物材料中具有極大的應(yīng)用潛力[2]。三元的Zr-Co-Al非晶合金的非晶形成能力(GFA)較差,臨界尺寸不到3 mm[3-4]。近幾年,科研者們向Zr-Co-Al系非晶合金中添加微量的Cu, Fe, Nb, Ag[5-8]等元素,希望提高其GFA和力學(xué)性能。
文獻(xiàn)[7]報(bào)道,通過(guò)向Zr-Co-Al中添加Nb元素可顯著提高耐蝕性能,卻使其GFA下降;文獻(xiàn)[8]中Ag元素的添加不僅提高了GFA,而且提高了耐蝕性,但Ag元素價(jià)格昂貴,故限制了Zr-Co-Al非晶合金的廣泛運(yùn)用。E.S.Park等[9]研究發(fā)現(xiàn),添加適量的稀土元素Y不僅能提高非晶合金的GFA和力學(xué)性能,而且可提高其耐蝕性。文獻(xiàn)[10]研究也發(fā)現(xiàn),在Zr55Al10Cu30Ni5中添加1% Y元素顯著提高了母合金在PBS溶液中的耐蝕性。文獻(xiàn)[11]報(bào)道,共晶點(diǎn)附近的Zr56Co28Al16非晶合金,臨界尺寸達(dá)到18 mm,GFA更好。本文在此基礎(chǔ)上,選取Zr56Co28Al16非晶合金作基體合金,向其中添加Y元素,對(duì)Zr-Co-Al-Y非晶合金在PBS溶液中的耐蝕性能進(jìn)行研究,并初步探討了添加Y元素引起耐蝕性變化的機(jī)理。
2實(shí)驗(yàn)
2.1試樣的制備
按名義成分配置(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)(以下分別簡(jiǎn)稱為試樣Y0, Y1, Y2和Y4)的母合金(材料純度均大于99.9%,質(zhì)量分?jǐn)?shù)),在高頻感應(yīng)磁懸浮熔煉爐(高純氬氣保護(hù))中反復(fù)熔煉3次,并采用銅模吸鑄法制備一系列直徑3 mm×70 mm的棒材(吸鑄功率為8 kW)。
2.2試樣的性能及表征
采用CS350電化學(xué)工作站三電極體系進(jìn)行電化學(xué)實(shí)驗(yàn),試樣做工作電極,鉑片(Pt)做輔助電極,飽和甘汞電極做參比電極(SCE)。測(cè)試過(guò)程均在310 K的模擬體液(PBS溶液,具體成分為:8 (g/L) NaCl,0.2 (g/L) KCl,0.14 (g/L) NaH2PO4,0.2 (g/L) KH2PO4,由分析純?cè)噭┖投卣麴s水配置)中進(jìn)行。實(shí)驗(yàn)前,將試樣浸入溶液中30 min后,測(cè)量開路電位,待穩(wěn)定后進(jìn)行極化曲線的測(cè)量。電化學(xué)腐蝕后的形貌用SEM(QUANTA FEG 450)觀察;運(yùn)用XPS(AXIS Ultra DLD)設(shè)備分析被腐蝕樣品表面的化學(xué)成分(真空環(huán)境為1×10-7Pa,激發(fā)光源為Mg Kα)。
3結(jié)果與討論
圖1為(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)試樣橫截面的XRD圖譜,試樣Y0,Y1和Y2圖譜在2θ=37°附近有一典型的非晶漫散射峰,在X射線有限分辨率內(nèi),沒有檢測(cè)到明顯的尖銳晶化峰,這表明樣品基本為非晶結(jié)構(gòu)。試樣Y4衍射圖譜有明顯的晶化峰,經(jīng)標(biāo)定為CoZr3、CoZr2和YAl3相。
圖1(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)試樣的X射線圖譜
Fig 1 X-ray diffraction patterns of (Zr56Co28Al16)100-xYx(x=0, 1, 2, 4) samples
圖2是(Zr56Co28Al16)100-xYx(x=0,1,2,4)試樣在310 K,PBS溶液中測(cè)得的極化曲線。從極化曲線可知,(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)試樣表現(xiàn)出相似的電化學(xué)行為,均在PBS溶液中發(fā)生了鈍化。表1列出了(Zr56Co28Al16)100-xYx(x=0,1,2,4)試樣的腐蝕參數(shù)。從表1可知,Y0試樣自腐蝕電位最正,自腐蝕電流密度最大,表明Zr56Co28Al16非晶合金的腐蝕傾向最小,但一旦發(fā)生腐蝕,自腐蝕速率最大。Y1試樣自腐蝕電位向負(fù)方向移動(dòng),腐蝕傾向增大,這使合金在腐蝕初期能夠快速均勻溶解,有利于保護(hù)膜的形成[12],但其自腐蝕電流密度最小,與母合金(Y0)相比低一個(gè)數(shù)量級(jí),點(diǎn)蝕電位最高,鈍化電流密度最低,表明Y1試樣表面最易形成鈍化膜。Y2試樣自腐蝕電位最低(-425 mV),鈍化區(qū)間最大(627 mV)。隨著Y元素的添加自腐蝕電位降低的原因可能是在Zr-Al-Co系中,Zr4++4e-?Zr(s)、Al3++3e?Al(s)和Co2++2e?Co(s)[13]的標(biāo)準(zhǔn)電極電勢(shì)(SEP)值均較Y元素高,而SEP越低意味著金屬更容易發(fā)生氧化反應(yīng),當(dāng)Zr-Co-Al-Y裸露在空氣中時(shí),Y元素最先發(fā)生氧化反應(yīng)。Y4試樣自腐蝕電位正移,但自腐蝕電流密度和鈍化電流密度與Y1、Y2試樣相比都增加了一個(gè)數(shù)量級(jí),耐蝕性卻下降。這是因?yàn)樵赮4試樣中,有晶體相的析出,在晶體相和非晶相界面處易成為晶界腐蝕敏感部位。另外,CoZr3、CoZr2和YAl3之間可能構(gòu)成腐蝕電偶,從而加速了樣品的腐蝕??偟脕?lái)說(shuō),適量Y元素的添加,顯著提高了非晶合金的耐蝕性能,但過(guò)量Y元素的添加導(dǎo)致非晶耐蝕性能降低。
圖2(Zr56Co28Al16)100-xYx(x=0,1,2,4)試樣PBS溶液37 ℃的極化曲線
Fig 2 Polarization curves for (Zr56Co28Al16)100-xYx(x=0,1,2,4) samples in PBS at 37 ℃
為作對(duì)比分析,表1列出了SS 316L和Ti-6Al-4V不銹鋼[14]的電化學(xué)參數(shù)。
表1 合金樣品在PBS溶液中的電化學(xué)參數(shù)
從表1可知,(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)試樣的自腐蝕電位、自腐蝕電流密度和鈍化電流密度較小,均低于SS316L不銹鋼,其中Y1、Y2的自腐蝕電流密度和鈍化電流密度與這兩種不銹鋼相比,均低1~2個(gè)數(shù)量級(jí)。非晶合金的耐蝕性能比SS 316L不銹鋼要優(yōu)異,但與Ti-6Al-4V不銹鋼相比,鈍化區(qū)間很短,表明在電位達(dá)到一定值后鈍化膜被擊穿,電流密度急劇增加。
圖3是(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)試樣腐蝕后的SEM形貌圖,Y0和Y4試樣有明顯的點(diǎn)蝕坑(見圖中左上角局部放大圖),Y4試樣腐蝕坑更多。Y1和Y2試樣腐蝕程度較輕,沒有明顯的點(diǎn)蝕坑。這表明,Y1和Y2試樣有更好的耐蝕性能,與極化曲線所表征的一致。
為了探索適量Y元素添加提高耐蝕性能的原因,選擇不添加Y元素的母合金Y0和擁有良好耐蝕性能的Y2進(jìn)行XPS對(duì)比分析,研究Y元素的添加對(duì)Zr56Co28Al16非晶電化學(xué)腐蝕行為的影響機(jī)理。XPS檢測(cè)表明,Y0、Y2試樣均存在Zr、Al、O、P的電子能譜峰,另外Y2有Y元素的電子能譜峰,但在Y0和Y2中都沒有檢測(cè)到Co元素,與文獻(xiàn)[15]一致,原因可能是Co元素具有最高的SEP值,在Ti-Zr-Cu-Pd-Sn, Ni-Pd-P-B和Zr-Co-Al-Ag非晶合金[16-18]鈍化膜研究結(jié)果中有相似的結(jié)論,Ti-Zr-Cu-Pd-Sn和Ni-Pd-P-B中Pd元素的SEP(0.9150 V)值最高,在鈍化膜中沒有檢測(cè)到惰性元素Pd,在Zr-Co-Al-Ag體系中,Ag具有最高的SEP(0.7996 V)值,因此在Zr-Co-Al-Ag體系中也沒有檢測(cè)Ag元素。文獻(xiàn)[1]中雖檢測(cè)到Co的能譜峰,但強(qiáng)度很微弱。在Y0、Y2試樣中沒有檢測(cè)到Cl元素峰,這表明形成的含Cl元素的腐蝕產(chǎn)物是易溶解的。精細(xì)譜如圖4(a)-(e)所示,分別為Zr3d、Al2p、O1s、P2p和Y3d。
圖3(Zr56Co28Al16)100-xYx(x=0, 1, 2, 4)試樣電化學(xué)腐蝕后的SEM圖
Fig 3 SEM photograph of (Zr56Co28Al16)100-xYx(x=0, 1, 2, 4) after electrochemical corrosion
圖4(Zr56Co28Al16)100-xYx(x=0,1,2,4)試樣鈍化膜中(a)Zr3d,(b)Al2P,(c)O1s, (d)P2p,(e)Y3d光電子能譜圖(其中黑色曲線為原始能譜曲線,彩色曲線為分峰擬合后的XPS曲線)
Fig 4 XPS spectra for (Zr56Co28Al16)100-xYx(x=0, 1, 2, 4) samples (a) Zr3d, (b) Al2P, (c) O1s, (d) P2p, (e) Y3d (black curves represent raw XPS spectra, and the colored one fitted curves)
表2鈍化膜的化學(xué)成分及其含量
Table 2 Compositions (at%) and chemical states of the passive films
合金ZrAlY氧化態(tài)金屬態(tài)氧化態(tài)氧化態(tài)PY053.361.7326.32018.59Y255.753.2931.060.59.40
4結(jié)論
(1)(Zr56Co28Al16)100-xYx(x=0, 1, 2)非晶合金在PBS溶液中均發(fā)生鈍化,自腐蝕電流密度與SS 316L和Ti-6Al-4V不銹鋼相比,低一個(gè)數(shù)量級(jí),耐蝕性優(yōu)于這兩種不銹鋼。
(2)添加適量Y元素,能顯著提高Zr56Co28Al16非晶合金的耐蝕性能;過(guò)量Y元素的添加,導(dǎo)致非晶基體上有晶體相CoZr3、CoZr2和YAl3的析出,耐蝕性能下降。
參考文獻(xiàn):
[1]Asahi Kawashima, Takeshi Wada,Kazuyo Ohmura, et al. A Ni-and Cu-free Zr-based bulk metallic glass with excellent resistance to stress corrosion cracking in simulated body fluids [J]. Materials and Engineering A, 2012, 542(30):140-146.
[2]Li D K, Zhu Z W, Zhang H F, et al. The influence of Zr substitution for Nb on the corrosion behaviors of the Ni-Nb-Zr bulk metallic glasses [J]. Physics, Mechanics & Astronomy, 2012, 55(12): 2362-2366.
[3]Zhang T, Inoue A. Formation, thermal and mechanical properties of bulk glassy alloys in Zr-Al-Co and Zr-Al-Co-Cu systems [J]. Materials Science and Engineering A, 2004, 375: 432-435.
[4]Zhang X F, Wang Y M, Qiang J B, et al. Optimum Zr-Al-Co bulk metallic glass composition Zr53Al23.5Co23.5[J]. Intermetallics, 2004, 12(10-11): 1275-1278.
[5]Wada T, Zhang T, Inoue A. Formation and high mechanical strength of bulk glassy alloys in Zr-Co-Al-Cu system[J]. Mater Trans Jim, 2003, 44(9): 1839-1844.
[6]Tan J, Pan F S, Zhang Y, et al.Effect of Fe addition on glass forming ability and mechanical properties in Zr-Co-Al-(Fe) bulk metallic glasses[J]. Materials Science and Engineering, 2012, 539(30): 124-127.
[7]Pang S J, Zhang T,Asami K, et al. Formation, corrosion behavior and mechanical properties of bulk glassy Zr-Al-Co-Nb alloys[J]. Mater Res, 2003, 18(7): 1652-1658.
[8]Zhang C, Li N, Pan J, et al.Enhancement of glass-forming ability and bio-corrosion resistance of Zr-Co-Al bulk metallic glasses by the addition of Ag[J]. Journal of Alloys and Compounds, 2010, 504S: S163-S167.
[9]Park E S, Kim D H. Phase separation and enhancement of plasticity in Cu-Zr-Al-Y bulk metallic glasses [J]. Acta Materialia, 2006, 54(10): 2597-2604.
[10]Huang L,Qiao D C, Brandice A, et al. Bio-corrosion study on zirconium-based bulk-metallic glasses [J]. Intermetallics, 2009, 17(4) 195-199.
[11]Wada T, Qin F X, Wang X M, et al.Formation and bioactivation of Zr-Al-Co bulk metallic glasses [J]. Mater Res, 2009, 24(9): 2941-2948.
[12]Yue L J, Xie K, Chen Y B, et al. Influence of micro-composition on the performance of Cu-Zr-Al bulk amorphous alloy[J]. Journal of Functional Materials, 2010, 41(S2):207-213.
[13]Vanysek P. Handbook of chemistry and physics, 88 ed[M]. Chemical Rubber Company, 2007.
[14]Lu Huang, Qiao D C, Brandice A, et al. Bio-corrosion study on zirconium-based bulk-metallic glasses[J]. Intermetallics, 2009, 17(4): 195-199.
[15]Zhang C, Li N, Pan J, et al. Enhancement of glass-forming ability and bio-corrosion resistance of Zr-Co-Al bulk metallic glasses by the addition of Ag[J]. Journal of Alloys and Compounds, 2010, 504(S1):163-167.
[16]Qin C L, Oak J J, Ohtsu N, et al. XPS study on the surface films of a newly designed Ni-free Ti-based bulk glass[J]. Acta Mater, 2007, 55(20): 2057-2063.
[17]Qin C L, Zeng Y Q, Louzguine D V, et al. Corrosion resistance and XPS studies of Ni-rich Ni-Pd-P-B bulk glassy alloys[J]. Journal of Alloys and Compounds, 2010, 504(S1): 172-175.
[18]Hua N B, Huang L, Wang J F, et al. Corrosion behavior and in vitro biocompatibility of Zr-Al-Co-Ag bulk glasses: an experimental case study [J]. Journal of Non-Crystalline Solids, 2012, 358(12-13): 1599-1604
[19]Asami K, Hashimoto K, Shimodaira S. XPS determination and the compositions of alloy surface and surface oxides on mechanically polished iron-chromium alloys [J]. Corrosion Science, 1977, 17(9): 713-723.
[20]Qiu C L, Liu L, Sun M, et al. The effect of Nb addition on mechanical properties, corrosion behavior, and metal-ion release of ZrAlCuNi bulk metallic glasses in artificial body fluid[J]. J Biomed Mater Res A, 2005, 75(4): 950-956.
Effects of yttrium additions on corrosion behavior of Zr56Co28Al16bulk metallic glasses in simulated body fluid
LI Ruiyang, YUAN Zizhou, KANG Jian, ZHANG Xiangyun
(State Key Laboratory of Gansu Advanced Processing and Recycling of Non-ferrous Metal,Lanzhou University of Technology, Lanzhou 710050, China)
Abstract:Ni-and Cu-free (Zr56Co28Al16)100-xYx(x=0, 1, 2, 4) bulk metallic glasses (BMGs) were successfully prepared by water-cooling copper mold technique. We have done detailed study about the effects of yttrium addition on corrosion behavior through X-ray diffraction (XRD), electrochemical workstation, scanning electron microscope(SEM) and X-ray photoelectron spectroscopy(XPS). The results indicated: moderate amount of yttrium addition can enhance the corrosion resistance of Zr-Co-Al-Y remarkably. The passive film is rich in Zr4+and Al3+, poor of , which is responsible for the enhanced corrosion. Much of adding deteriorated the corrosion resistance of Zr-Co-Al-Y because of the precipitation of crystal phase.
Key words:Zr-based bulk metallic glass; simulated body fluid; corrosion resistance; XPS
DOI:10.3969/j.issn.1001-9731.2016.01.032
文獻(xiàn)標(biāo)識(shí)碼:A
中圖分類號(hào):TB332(TG174.2; TG139+.8)
作者簡(jiǎn)介:李銳陽(yáng)(1989-),男,湖北宜昌人,碩士研究生,師承袁子洲教授,從事非晶合金研究。
基金項(xiàng)目:國(guó)家自然科學(xué)基金資助項(xiàng)目(51061008)
文章編號(hào):1001-9731(2016)01-01159-04
收到初稿日期:2015-01-22 收到修改稿日期:2015-08-18 通訊作者:袁子洲,E-mail: lut305@163.com