稀土Gd对FeCrMoCB合金非晶形成能力及力学性能的影响

通过添加不同含量的稀土Gd,采用铜模真空吸铸法制备出一系列直径不同的FeCrMoCBGd合金样品,借助X射线衍射仪(XRD)、示差扫描量热仪(DSC)、显微硬度仪及万能试验机,研究了添加稀土元素Gd对FeCrMoCB合金非晶形成能力及力学性能的影响.结果表明,当Gd添加量为2%(原子分数)时,FeCrMoCBGd系合金的非晶形成能力最好,非晶合金的最大直径可超过12mm;非晶合金系的晶化过程为二级晶化行为,其显微硬度随直径的增加呈下降趋势,随Gd含量的增加而增加;非晶合金系均表现为脆性,断裂方式为典型的脆性断裂.     

Fe60Co8Zr10Mo5W2B15块体非晶合金的形成及热处理对性能的影响研究

用铜模吸铸法获得直径为2mm的Fe60Co8Zr10Mo5W2B15和Fe60Co8Zr10Mo5W2B15块体非晶合金。采用X射线衍射（XRD）、示差扫描量热分析（DSC）、显微硬度及压缩实验等研究了非晶合金的结构、热稳定性及热处理前后的显微硬度与压缩性能。结果表明Nb的引入不利于非晶合金的形成；Fe60Co8Zr10Mo5W2B15非晶合金的显微硬度为1343HV0．2，抗压强度σbe为972．6MPa；在低于晶化起始温度的热处理，硬度稍有下降；但在高于晶化峰值温度的热处理，硬度值随时间变化先升高，后下降；在热处理时间相同的条件下，随着热处理温度的升高，合金的硬度升高，但压缩强度会明显下降。     

CuZrNb块体金属玻璃的形成能力和低温电阻的研究

采用铜模吸铸方法制备出直径为1mm的Cu60Zr40-xNbx(x=2,5,8)合金。对合金的结构分析表明,Nb含量的改变对合金非晶形成能力有很大影响,当Nb含量为5%(原子百分比)时,合金可以形成完全非晶。低温电阻测试结果表明,Nb含量的变化会明显改变合金的低温电阻率,Nb含量为2%时,合金的电阻率随温度下降而上升,而含量为5%和8%时,电阻率随温度下降而下降。与晶化前相比,Cu60Zr35Nb5块体金属玻璃晶化后电阻率较晶化前有所降低,在低温时由非晶态的部分超导转变为晶化态的超导。     

Fe61Co10Zr5W4B20块体非晶合金的形成及其力学性能

采用铜模吸铸法获得直径为2 mm的Fe61Co10Zr5W4B20块体非晶合金.采用X射线衍射、扫描电镜、示差扫描量热仪、微显硬度及压缩实验等研究了非晶合金的结构、热稳定性、显微硬度与压缩性能.结果表明:Mo的引入不利于非晶合金的形成;Fe61Co10Zr5W4B20块体非晶合金表现为二级晶化,玻璃转变温度为561.1℃,晶化起始温度为619.0℃,第一晶化峰值温度为632.6℃,第二晶化峰值温度为747.0℃,过冷液相区为57.9℃;该非晶合金的显微硬度为1207HV0.2,抗压强度σbc为1707.6 MPa.     

重稀土元素添加对Cu-Zr-Al合金非晶形成和力学性能的调控

稀土元素是改善非晶态合金形成能力和性能的重要添加剂,本文采用铜模吸铸法制备了一系列Cu_(50-x)Zr_(46)Al_4RE_x(RE=Dy,Tb,Gd;x=0,1,2,3,4)非晶态合金,系统地探究了重稀土元素Dy、Tb、Gd添加对Cu-Zr-Al合金非晶形成能力(GFA)和力学性能的影响。实验结果表明加入重稀土元素Dy、Tb、Gd后,合金系的玻璃转变温度显著降低,而过冷液相区宽度ΔT_x(ΔT_x=T_x-T_g)增大,1%(原子分数)的Dy、Tb和3%(原子分数)的Gd添加获得了最大的γ=T_x/(T_g+T_l)参数值,表明合适的添加量有利于合金非晶形成能力的提高。同时,适量的Dy、Tb、Gd引入可以显著提高Cu-Zr-Al合金的塑性变形能力。硬度和γ参数随稀土元素含量的变化呈现相似的变化趋势,表明非晶形成能力与硬度之间存在一定的关联性。稀土元素添加导致非晶态合金样品硬度呈现更大的径向不均匀性,有利于合金塑性变形能力的提高。     

Zr_(50-x)Cu_(50)Al_x(x=0～25)合金中的二十面体团簇以及Al添加对非晶形成能力和结构转变的影响

采用X射线衍射(XRD)和扫描电子显微镜(SEM)技术研究了Al元素的添加以及二十面体团簇结构对不同冷却速率下Zr50-xCu50Alx(x=0～25)合金的非晶形成能力、合金结构以及相变过程的影响。结果表明,对直径3mm的Zr45Cu50Al5合金,其主相为ZrCu和二十面体相,而对于直径为3mm的Zr45Cu50Al5合金,其主相则为ZrCu和非晶相。二十面体相的衍射峰强度随着冷却速率的增加而大大降低,直至变成弥散峰。反映出二十面体相与非晶相之间存在强烈的关联性。Zr-Cu-Al合金中的非晶相与二十面体相具有相同的短程有序结构,即二十面体团簇结构,这种5次对称的原子堆垛结构与周期性有序的晶体结构互不相容,从而起到阻碍结晶、提高非晶形成能力的作用。     

Fe-Nd-B-Zr块体非晶合金的形成能力和磁性能

以Fe-Nd-B系块体非晶合金为前驱体制备永磁材料。在Fe70Nd10B20三元合金及其邻近成分点中微量添加Zr元素,采用熔体旋淬法和铜模喷注法制备样品,通过XRD和DSC表征非晶形成能力。对Fe70Nd9B20Zr1块体非晶合金进行退火晶化处理,采用XRD分析晶化产物,通过VSM表征不同晶化阶段的磁性能。结果表明,合金体系的非晶形成能力得到提高,在Zr原子分数为1%时获得临界尺寸为2mm的块体非晶合金;Fe70Nd9B20Zr1块体非晶合金在946K,600s退火时得到最佳硬磁性能,剩磁(Br)、内禀矫顽力(iHc)和最大磁能积(BH)max分别为0.54T,348kA/m和24.1kJ/m3。该合金体系可应用于直接通过铸造和热处理工艺制备块体纳米复合永磁材料。     

Y添加Ti_(40)Zr_(25)Cu_9Ni_8Be_(18)非晶合金的纳米晶化及力学性能

利用铜模铸造法制备直径为3mm的(Ti_(40)Zr_(25)Cu_9Ni_8Be_(18))100-xYx(x=0,1.0,1.5,2.0,3.0)合金棒材,采用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、差式扫描量热计(DSC)和单轴压缩测试设备对合金的组织、玻璃形成能力和力学性能进行研究。结果表明:Y元素含量为1.0%(原子分数,下同)时,合金的衍射结果为非晶态;Y元素含量为1.5%时,诱发了非晶合金的纳米晶化。在高分辨透射电镜下可观察到,非晶基体上析出5~20nm左右的晶化相,含Y为1.5%的合金抗压强度高达1990MPa,塑性应变高达3.0%;Y添加后合金断口处剪切带数量增加。多剪切带之间的交错,阻碍不均匀形变,提高了合金的塑性和强度。     

Ti-Zr-Cu-Co-Sn-Si块体非晶合金的形成及生物腐蚀行为和力学性能

采用铜模铸造法制备了不含高生物毒性元素Ni和Be及贵金属元素的生物医用型Ti87-xZr7.5CuxCo2.5Sn2Si1(x=39,40,42,原子分数/%)块体非晶合金,并对其非晶形成能力、热稳定性、生物腐蚀行为及力学性能进行了研究。结果表明:该系非晶合金临界直径为2~3mm,并具有较高的热稳定性,其过冷液体温度区间为44~51K。Ti-Zr-Cu-Co-Sn-Si非晶合金在模拟人体体液环境中表现出高耐腐蚀性能,在37℃的磷酸盐缓冲溶液中发生自钝化,钝化电流密度低,且其开路电位和孔蚀电位随着Ti含量的增加而提高。该系非晶合金具有良好的力学性能,压缩断裂强度达2309MPa,弹性模量为92~100GPa。     

Zr基块体非晶合金玻璃形成能力与压铸成型性能研究

本文分析了熔体温度、铸造压力和化学成分对非晶合金玻璃形成能力(GFA)与压铸成型性能的影响,并探究两种性能的工艺关联。研究发现:随熔体温度升高,Zr基非晶合金GFA先提高后减小,且合金成分不同,熔体化学成分,局域原子团簇特征和合金实际冷却速率就不同,非晶合金GFA与玻璃稳定性也就存在差异。非晶合金的压铸成型能力随熔体温度和铸造压力升高不断提高,但与GFA存在相互限制的作用:当合金GFA较强时,熔体内原子堆垛密实,粘滞系数较高严重阻碍过冷液流动成形,且玻璃稳定性越好压铸成型性能越差;而当熔体温度过高,非晶合金GFA减弱,过冷液粘度降低时,才能快速提高非晶合金的压铸成型性能。因此,选择最佳的合金成分、优化工艺参数有利于非晶精密结构件成型。     

Glass-Forming Ability for Nd_(70-x)Fe_(20)Al_(10)Y_x and Nd_(60-x)Fe_(30)Al_(10)Y_x Alloys

The glass-forming ability (GFA) of Nd70-xFe2oAl10Yx and Nd60-xFe30Al10Yx (0< x <15) alloys produced by Cu mold casting was investigated. Except Y=5 at. pct, bulk amorphous Nd70-xFe20Al10Yx alloys up to 2 mm in diameter were obtained. The GFA for Nd60-xFe30Al10Yx alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy. The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, Tg, and the supercooled liquid region, TX, are 776 K and 58 K, respectively. The GFA and thermal stability of the Nd-Fe-AI-Y a     

Glass-Forming Ability for Nd70-xFe20AlioYx and Nd60-xFe30Al10Yx Alloys

The glass-forming ability (FGA) of Nd70-xFe20Al10Yx and Nd60-xFe30Al10Yx(0≤x≤15) alloys produced by Cu mold casting was investigated.Except Y=5 at.pct,bulk amorphous Nd70-xFe20Al10Yx alloys up to 2mm in diameter were obtained.The GFA for Nd60-xFe30Al10Yx alloys,however,was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy.The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3mmm in diameter.The melting temperature or /and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys.The bulk amorphous c ylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization.The crystallization temperature,Tg,and the supercooled liquid region,ΔTx,are 776K and 58K,respectively,The GFA and thermal stability of the Nd-Fe-Al-Y alloys were discussed.     

Effect of Nb addition on the glass forming ability and mechanical properties in the Ni-Zr-Al-Hf-Nb alloys

The effect of substituting Nb for Zr on the glass forming ability (GFA) and mechanical properties of Ni₆₀ Al₆Hf₇ (x = 0 -- 14) alloys was investigated. The substitution of Zr with Nb of 0 -- 14 at% improved the GFA. When increasing the Nb content x from 0 -- 14, the glass transition temperature, T_g, and the crystallization temperature, , of melt-spun Ni₆₀ Al₆Hf₇ (x = 0 -- 14) alloys increased from 833 and 863 K to 877 and 914 K, respectively. The Ni₆₀ Al₆Hf₇ (x = 8, 10, 12 and 14) alloys exhibited high (>0.615), (>0.4) values and a wide supercooled liquid region, (= – T_g) (>36 K) enabling the fabrication of bulk metallic glass (BMG) with a diameter above 1 mm. As such, Ni₆₀Zr₁₇Al₆Hf₇Nb₁₀ and Ni₆₀Zr₁₅Al₆Hf₇Nb₁₂ alloys with a maximum diameter of 2 mm could be fabricated by injection casting. These bulk amorphous alloys also exhibited good mechanical properties, where the true ultimate compressive strength, strain and Vickers hardness (H_v) were approximately 3.0 GPa, 2.08% and 713, respectively, for the amorphous Ni₆₀Zr₁₇Al₆Hf₇Nb₁₀ alloy, and 3.1 GPa, 2.22% and 687, respectively, for the amorphous Ni₆₀Zr₁₅Al₆Hf₇Nb₁₂ alloy.     

Complete Composition Tunability of Cu(Ni)-Ti-Zr Alloys for Bulk Metallic Glass Formation

In the Cu-Zr-Ti ternary system, a new composition zone of bulk metallic glasses (BMGs) formation was discovered, locating at the 55-57 at. Pct Cu, 30-31 at. Pct Ti and 13-14 at. Pct Zr, and near Cu-Ti binary subsystem rather than the Cu-Zr binary. For these alloys, BMG rods of 2 mm in diameter can be fabricated by using copper mould casting. It is expected that these BMG-forming alloys correlate with (L→CuTi+Cu2TiZr+Cu61Zr14) eutectic reaction that the undercooled melt undergoes during solidification. Adopting "3D pinpointing ap-proach", compositional dependence of glass-forming ability (GFA) in Cu(Ni)-Ti-Zr pseudo ternary system was revisited. Optimized BMG-forming composition is located at Cu50.4Ni5.6Ti31Zr13, with a critical diameter of 6 mm for complete BMG formation. Its GFA is significantly superior to Vit 101 (Cu47Ni8Ti34Zr11) previously developed by Caltech group. The effect that the GFA of the ternary base alloy was improved by substitution of Ni for Cu is attributed to a role of retarding the crystallization of Cu51Zr14 intermetallics.     

微量Al添加对铜基大块非晶合金性能的影响

为了进一步提高铜基大块非晶合金的玻璃形成能力及力学性能,采用添加微量Al元素的方法对块体非晶合金Cu52.5Ti30Zr11.5Ni6进行了成分优化.热分析与X射线衍射结果显示,随着微量Al的添加,液相线温度从非晶合金Cu52.5Ti30Zr11.5Ni6的1150 K逐步降低到Cu50.5Ti30Zr11.5Ni6Al2的1134 K,临界直径相应的从5 mm提高到6 mm.大块非晶Cu50.5Ti30Zr11.5Ni6Al2的压缩断裂强度达到2286 MPa,比经典的铜基非晶合金Cu47Ti34Zr11Ni8提高约100 MPa,表明微量Al的添加在有效提高玻璃形成能力的同时,强度也略有提高.     

Quaternary Ti–Zr–Be–Ni bulk metallic glasses with large glass-forming ability

The glass-forming ability (GFA) of Ti–Zr–Be ternary alloys is dramatically improved by partially replacing Be with Ni. Centimeter-scale fully amorphous samples can be obtained in a wide Ni content range of 4 at.%–12 at.%. In particular, some of the developed Ti–Zr–Be–Ni alloys exhibit a critical diameter up to 20 mm, which is larger than that of other quaternary Ti-based bulk metallic glasses (BMGs). Moreover, Ni addition also enhances the yield strength and compressive plastic strain of Ti–Zr–Be alloys obviously. Based on the experimental results, the effect of substituting elements addition on the glass-forming ability of Ti–Zr–Be alloys has been systematically investigated and an empirical composition design method for the development of novel Ti-based BMGs with large GFA has been proposed.     

FeCoZrNbB合金的晶化过程及磁性能

采用单辊快淬法制备Fe_81-xCo_xZr₇Nb₂B₁₀(x = 2, 4, 6) 系非晶合金,并对该系非晶合金进行热处理。利用X射线衍射和振动样品磁强计研究FeCoZrNbB 合金系的晶化过程和磁性能。结果表明,Fe_81-xCo_xZr₇Nb₂B₁₀(x = 2, 4, 6) 系合金在快淬速率为30 m/s时完全形成非晶。Fe₇₉Co₂Zr₇Nb₂B₁₀合金的晶化过程为非晶→非晶+α-Fe→α-Fe + Fe₃Zr + Fe₂Nb_0.4Zr_0.6;Fe₇₇Co₄Zr₇Nb₂B₁₀与Fe₇₅Co₆Zr₇Nb₂B₁₀合金的晶化过程相同为非晶→非晶+α-Fe→ α-Fe + Fe₃Zr →α-Fe + Fe₃Zr + Fe₂Nb_0.4Zr_0.6。Co 含量的增加抑制了退火后α-Fe晶相的形核,并促使Fe 3Zr化合物更易析出。Fe_81-xCo_xZr₇Nb₂B₁₀(x = 2, 4, 6) 合金的比饱和磁化强度( M_s) 和矫顽力 ( H_c) 随退火温度的变化趋势相同。530℃ 之前退火,随退火温度的升高M s增加并不明显 ; 530℃之后退火,M_s迅速上升。530℃ 退火,H_c达到最小值;高于530℃ 退火,H_c随退火温度的升高而增加。      

Superconductivity of Ni-Nb-Zr-H glassy alloys with nanoclusters

We investigated the hydrogen effect on superconductivity in the (Ni0.36Nb0.24Zr0.40)(100-x)H(x)(0 < or = x < or = 6.4) glassy alloys with nanoclusters, as a function of temperature. The resistivity of these alloys started to drop from onset temperature of around 9.5 K. The (Ni0.36Nb0.24Zr0.40)98.6H1.6 showed zero resistance at 2.1 K. However, the application of a magnetic field > 4.6 T arrested the drop of resistivity, showing the existence of superconductivity of type II. The maximum onset temperature of 11.3 K was observed at 4.4 at% H. The superconducting behavior of the glassy alloys would be associated with electron pair transport along zigzag paths, which link the shortened atomic -Ni-Ni-Ni- array in the Zr5Ni5Nb3 clusters, and tunneling among the clusters.     

Effect of Pd on GFA and Thermal Stability of Zr-based Bulk Amorphous Alloy

The effect of Pd addition on the glass-forming ability and thermal stability of the Zr55Al10Cu30Ni5-xPdx (x=0, 1, 3, 5 at. pct) alloys upon copper-mold casting has been investigated. The structure, thermal stability and microstructure were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), respectively. It was identified that a new bulk amorphous alloy with the larger supercooled liquid region Tx of 100 K is obtained with substituting Ni by 1 at. pct Pd. Furthermore, the origins that thermal stability and GFA change with increasing of Pd have also beer discussed.     

Microstructures and crystallization of electroless Ni-P deposits

A study has been made of microstructures and crystallization of the electroless Ni-P deposits containing 11.3 to 23.0 at% P obtained from acidic nickel sulphate baths with sodium hypophosphite as a reducing agent by means of differential scanning calorimetry, X-ray diffractometry and hot stage transmission electron microscopy. The deposits containing low phosphorus content of 11.3 at% could be represented as an fcc Ni-P solid solution of 5 to 10 nm microcrystallites, whereas the deposits containing high phosphorus content were amorphous. The crystallization process of amorphous Ni-P solution involved more than one intermediate phases; precrystallized nickel or off-stoichiometric Ni₃(P, Ni) or Ni₅(P, Ni)₂ phase in which some phosphorus sites are replaced by nickel atoms. The final equilibrium phases were bct Ni₃P and fcc nickel crystals regardless of phosphorus content. The amorphous phase containing 20 to 22 at% phosphorus was the most stable among the amorphous Ni-P alloys.