Effect of Ce addition on microstructure of Mg–9Li alloy

The as-cast and as-extruded Mg–9Li, Mg–9Li–0.3Ce alloys were respectively prepared through a simple alloying process and hot extrusion. The microstructures of these alloys were investigated by optical microscope (OM), scanning electron microscope (SEM), X-ray diffractometer (XRD) and energy dispersive spectrometer (EDS). The results indicate that Ce addition produces a strong grain refining effect in Mg–9Li alloy. The grain size of the as-extruded alloy reduces abruptly from 88.2 μm to 10.5 μm when the addition of Ce is 0.36%. Mg₁₂Ce is verified and exists inside the grains or at the grain boundaries, thus possibly pins up grain boundaries and restrains the grain growth.     

杂质Ca对Al-5Mg填充合金凝固组织及力学性能的影响

结合拉伸试验和冲击试验,采用SEM、EDS和XRD等分析方法研究了杂质元素Ca对铝镁焊接填充合金铸态凝固组织和力学性能的影响。结果表明,Ca元素的存在改变了合金相组成。当Ca小于0.28%,合金中晶界富集由块状(Ti,Cr)₂Ca(Al,Mg)₂₀金属间化合物相。当Ca大于等于0.28%时,块状(Ti,Cr)₂Ca(Al,Mg)₂₀相和不连续条状Al₂Ca相共同在晶界富集。随Ca含量的增加,合金中块状相和条状相尺寸逐渐增大,数量逐渐增加。合金抗拉强度随Ca元素的增加先升高再降低,Ca含量0.28%时抗拉强度达到峰值。Ca小于0.28%时,合金塑性和冲击韧性缓慢下降,当Ca大于0.28%时,条状Al₂Ca相和块状(Ti,Cr)₂Ca(Al,Mg)₂₀相在晶界共存,低应力下两相破裂成为裂纹源,Al₂Ca硬脆相削弱了晶间结合强度,合金塑韧性大幅下降。合金拉伸或冲击断口由穿晶延性断裂(Ca<0.28%)转变为脆性断裂(Ca>0.28%)。Ca含量0.28%为合金韧脆转变点。     

Mg58Al42储氢合金的制备及其电化学性能

采用机械合金化技术制备了Mg58Al42储氢合金并借助于X射线衍射仪、PARM273A和M5210电化学综合测试仪研究了其在不同球磨时间下的物相结构以及放电容量和耐腐蚀等电化学性能. 结果表明:合金粉末经高能球磨后产生了Mg17Al12新相,随着球磨时间的增加,衍射峰的相对强度下降,衍射峰变宽,合金的平均晶粒尺寸降低,内应力增大.合金的放电容量随球磨时间的延长先增加而后则降低,其中球磨20 h时,放电容量最大.合金的动电位极化曲线出现了钝化现象,合金腐蚀电流密度随球磨时间的延长先增大而后降低.合金的交流阻抗谱均由单容抗弧组成,电极反应受合金/电解质溶液界面的电荷迁移所控制.     

THERMAL STABILITY OF THE MECHANICALLY ALLOYED Al－10Ti NANOCRYSTALLINE ALLOY DURING CONSOLIDATION PROCESS

ＴＨＥＲＭＡＬＳＴＡＢＩＬＩＴＹＯＦＴＨＥＭＥＣＨＡＮＩＣＡＬＬＹＡＬＬＯＹＥＤＡｌ－１０ＴｉＮＡＮＯＣＲＹＳＴＡＬＬＩＮＥＡＬＬＯＹＤＵＲＩＮＧＣＯＮＳＯＬＩＤＡＴＩＯＮＰＲＯＣＥＳＳＬｉａｎｇＧｕｏｘｉａｎ；ＬｉＺｈｉｃｈａｏ；ＷａｎｇＥｒｄｅ（...     

B2O3对铸态Mg-Al-Ti-B合金的显微组织与力学性能的影响

采用机械合金化制备的 Mg?Al?Ti?B 合金,其微观组织的均匀性较差,而且致密性也不好。为了提高Mg?Al?Ti?B合金微观组织的均匀性和致密性,使其力学性能得到改善,制备了铸态Mg?9Al?6Ti合金。采用金相显微镜、扫描电镜、X射线衍射与力学性能测试等手段,研究B2O3对Mg?9Al?6Ti (质量分数,%)合金的显微组织与力学性能的影响。结果表明：添加3%的B2O3使Mg?Al?Ti?B合金的晶粒尺寸减小到12μm,Ti颗粒完全消失,沉淀相Mg17Al12减少,而TiAl3相增多。由于新沉淀相MgB6和Ti3B4的析出,Mg?9Al?6Ti?3B2O3合金的结构变得均匀,平均硬度为HV77.1,平均抗拉强度、屈服强度和伸长率分别是171.2 MPa、113.5 MPa和5.2%。     

Electrochemical characteristics of Mg2−xZrxNi (x = 0–0.6) electrode alloys prepared by mechanical alloying

The electrode alloys Mg_2−xZr_xNi (x = 0, 0.15, 0.3, 0.45 and 0.6) were prepared by mechanical alloying (MA). Mg in the alloy was partially substituted with Zr in order to improve the electrochemical characteristics of the Mg₂Ni-type alloy. The microstructures and the electrochemical characteristics of the experimental alloys were measured systemically. The effects of substituting Mg with Zr and MA technique on the microstructures and electrochemical performances of the alloys were investigated in detail. The results obtained by XRD, SEM and TEM show that the substitution of Zr is favourable for the formation of an amorphous phase. For a fixed milling time, the amorphous phase in the alloy grows with increasing Zr content. The electrochemical measurement indicates that the substitution of Zr can dramatically enhance the discharge capacity with preferable cycle stability, and it markedly improves the discharge voltage characteristic of the alloys. For x ≤ 0.3, the discharge capacity of the alloys monotonically increases with milling time. But for x > 0.3, it has a maximum value with the change of milling time.     

机械合金化制备Cu-Cr合金时效强化特性的研究

采用机械合金化工艺制成Cu—Cr合金粉末,然后热压成形制备铜铬合金。采用XRD、TEM分析机械合金化过程中Cu-Cr合金粉末的显微组织和晶粒大小,测试了热压成形后Cu—Cr合金的力学和电学性能,探讨了材料的强化机制和热压温度对组织性能的影响。结果表明,Cu—Cr合金粉末可通过机械合金化获得过饱和固溶体,热压成形后,组织细小均匀,具有优良的综合性能。该合金经840℃热压并保温2h后,其强度达最大值,显微硬度为205．3HV,抗拉强度633．5MPa,电导率为80．4％IACS。合金中过饱和的Cr原子的作用是使合金沉淀强化。     

Enhanced mechanical properties and formability of hot-rolled Mg–Zn–Mn alloy by Ca and Sm alloying

In order to broaden the application of wrought Mg alloy sheets in the automotive industry, the influence of Ca and Sm alloying on the texture evolution, mechanical properties, and formability of a hot-rolled Mg–2Zn–0.2Mn alloy was investigated by OM, XRD, SEM, EBSD, tensile tests, and Erichsen test. The results showed that the average grain size and basal texture intensity of Mg–2Zn–0.2Mn alloys were remarkably decreased after Ca and Sm additions. 0.64 wt.% Ca or 0.48 wt.% Sm addition significantly increased the tensile strength, ductility and formability. Moreover, the synergetic addition of Sm and Ca improved the ductility and formability of Mg–2Zn–0.2Mn alloy, which was due to the change of Ca distribution and further reduction of the size of Ca-containing particles by Sm addition. The results provided a possibility of replacing RE elements with Ca and Sm in Mg alloys which bring about outstanding mechanical properties and formability.     

An improved practice to manufacture Al–Ti–B master alloys by reacting halide salts with molten aluminium

The well-established “halide salt” route was employed in the present work to produce Al–Ti–B grain refiner alloys with consistent, good properties. The holding step in the production cycle was revised, however, to avoid oxidation of the molten alloy which is believed to be responsible for the relatively low Ti recoveries and thus for the inadequate and inconsistent grain refining efficiency. Stirring during holding was found to degrade the grain refining properties when molten potassium aluminium fluride salt was left on the molten alloy to avoid excessive oxidation. Likewise, holding temperatures higher than 800 °C and holding times longer than 30 min both had an undesirable effect on the grain refining performance. The experimental Al–5Ti–1B grain refiner alloy produced according to the present method provided consistent and better overall grain refining performance.     

Deformation of nanocrystalline binary aluminum alloys with segregation of Mg,Co and Ti at grain boundaries

The influence of the temperature and sort of alloying element on the deformation of the nanocrystalline (NC) binary Al alloys with segregation of 10.2 at % Ti, Co, or Mg over grain boundaries has been studied using the molecular dynamics. The deformation behavior of the materials has been studied in detail by the simulation of the shear deformation of various Al bicrystals with the grain-boundary segregation of impurity atoms, namely, Ti, Co, or Mg. The deformation of bicrystals with different grain orientation has been studied. It has been found that Co introduction into grain boundaries of NC Al has a strengthening effect due to the deceleration of the grain-boundary migration (GBM) and difficulty in the grain-boundary sliding (GBS). The Mg segregation at the boundaries greatly impedes the GBM, but stimulates the development of the GBS. In the NC alloy of Al–Ti, the GBM occurs actively, and the flow-stress values are close to the values characteristic of pure Al.     

喷射沉积Mg-12.55Al-3.33Zn-0.58Ca-1.0Nd合金组织与力学性能研究

利用XRD、OM、SEM、TEM研究了喷射沉积Mg-12.55Al-3.33Zn-0.58Ca-1.0Nd合金挤压态的显微组织和合金的力学性能。结果表明:喷射沉积挤压态镁合金主要包含基体α-Mg和Al2Ca相,基体组织为等轴晶,平均晶粒尺寸为3μm;Al2Ca颗粒主要沿镁基体晶界分布,颗粒尺寸在1.0μm左右,并在Al2Ca相中存在孪晶结构;合金的σb、σ0.2、δ分别为450、325MPa,5%。在拉伸断口上存在大量石块状的Al2Ca相,表明合金的断裂方式为沿晶断裂;与经热挤压的铸造AZ91镁合金对比,该合金强度明显提高,但合金塑性降低;合金强度的提高主要来源于合金的细晶强化和Al、Zn对合金的固溶强化,而伸长率降低是由于合金中存在的大量Al2Ca颗粒是沿镁基体晶界分布,导致合金的塑性降低。     

热处理工艺对ZC63镁合金组织及性能的影响

利用光学显微镜、X射线衍射仪、扫描电镜和力学万能试验机等研究了ZC63镁合金在不同热处理工艺下的显微组织和力学性能的变化规律。结果表明:ZC63镁合金铸态组织主要由α-Mg和呈网状分布的CuMgZn相组成;经热处理后,强化相主要由颗粒状的CuMgZn和Mg2Zn3相组成。实验合金在445℃固溶24 h后,随着时效温度的升高,合金的抗拉强度和硬度值都逐渐降低,但在180℃时效20 h,伸长率最高,达到17.2%。热处理后合金的拉伸断口形貌中分布有颗粒状CuMgZn析出相,阻碍了晶界和位错的运动,裂纹沿着颗粒状析出相的边界以及内部扩展。     

Structural,Optical, and Ferroelectric Behaviors of Cu_(1-x)Li_xO(0≤x≤0.09) Nanostructures

We report structural,optical,and ferroelectric behaviors of lithium-doped copper oxide(Cu1-xLixO with x =0.0,0.05,0.07,and 0.09) nanostructures synthesized by hydrothermal method.The XRD pattern indicates the pure phase formation of CuO without any impurity,and the crystallite size is found to be increases for x =0–0.07 and decreases for x =0.09.FESEM analysis shows that the average size of Cu1-xLixO nanostructures increases with the increasing the Li-doping concentrations up to 7% and then decreases for 9% Li doping concentration.Moreover,Raman and photoluminescence spectrum also confirm the phase formation of CuO.A significant reduction in optical band gap is observed up to x =0.07,and then band gap increases for x =0.09 due to segregation of the impurities on the surface or grain boundaries,which may suppress the grain growth and results the enhancement in optical band gap.Moreover,a weak ferroelectricity is observed in CuO nanostructures for pure and 9% Li doping through polarization versus electric field(P–E).     

机械合金化Al—Mg—Si—Cu元素粉末的特性

Al,Mg,Si和Cu元素粉末按6061铝合金成分配比进行了机械合金化（MA）,对其物相、合金化特性、晶格常数、晶粒尺寸及点阵应变作了测定和分析讨论。MA初期晶粒尺寸可以达到纳米级,最小晶粒尺寸20nm;粉末点阵应变最终达0．2％;Al晶格常数变化的总趋势是不断减小;塑性较好的元素粉末可在“面上”作短程扩散,合金化易于进行,可实现完全合金化;硬度较高的脆性元素粉末可在“面上”作短程扩散,合金化易于进行,可实现完全合金化;硬度较高的脆性元素粉末只在“点上”作短程扩散,合金化不易进行,难以实现完全合金化。     

The performance of Al–Ti–C grain refiners in twin-roll casting of aluminium foilstock

The master alloys based on the Al–Ti–B system have been used extensively for refining the grain structure of aluminum alloys. The quality-related problems linked with the TiB₂ particles, however, have generated an interest in the Al–Ti–C grain refiners as an acceptable replacement for Al–Ti–B master alloys. TiC particles are smaller than the TiB₂ particles and are less prone to agglomeration. Al–3Ti–0.15C grain refiners have been in use for some time in several alloy systems. Much of the work reported on this alloy, however, has been from DC casting while performance data in strip casting is not available. In the present work, a commercial Al–3Ti–0.15C grain refiner was employed in the twin-roll casting of AA8111 foilstock. Its grain refining efficiency was compared with that of the Al–5Ti–0.2B master alloy, the standard grain refiner in aluminium industry for the manufacture of aluminium foil products.     

CrFeCoNiB0.05Tix高熵合金的显微组织和力学性能

采用机械合金化和放电等离子烧结工艺制备了CrFeCoNiB_0.05Ti_x(x=0.2、0.4、0.6、0.8、1.0)高熵合金材料,通过X射线衍射分析、扫描电镜观察和能谱分析以及维氏硬度测试和压缩强度测试等,研究了Ti含量对高熵合金微观组织和力学性能的影响。结果表明,CrFeCoNiB_0.05Ti_x(x=0.2、0.4、0.6、0.8、1.0)高熵合金由FCC、BCC和α相组成。当x=1.0时,合金由BCC结构转向HCP结构并析出新相Laves相,其具有最高硬度416.54 HV0.2。当x=0.8时,合金达到最大抗压强度586.3 MPa。     

掺Pd改性纳米晶Mg2Ni吸放氢氘特性研究

采用机械合金化法制备了Mg2Ni-1．0％Pd（质量分数，下同）合金粉末，用XRD及AFM等分析表征了球磨20h后粉末的相结构和微观形貌，测定了Mg2Ni-1．0％Pd合金吸放氢氘的P-C-T曲线和动力学曲线。结果表明，机械合金化制备的Mg2Ni-1．0％Pd合金粉末粒度在10nm～50nm之间；同熔炼法制备的Mg2Ni合金相比，纳米Mg2Ni-1．0%Pd合金吸氢时的焓变值减小，放氢时焓变值增大，可逆贮氢容量为1．06（H／M,原子比，下同）；与吸放氢相比，在相同温度下合金吸放氘的坪台压升高，焓变值减小，具有显著的同位素效应。纳米Mg2Ni-1．0％Pd合金的吸氢速率和吸氘速率与温度的关系在573K附近发生变化。     

Synthesis of TiB_2 TiC by mechanical alloying

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉＢ2 ａｎｄＴｉＣａｒｅｂｏｔｈｓｔａｂｌｅｃｏｍｐｏｕｎｄｓｗｉｔｈｃｅｒｔａｉｎｏｆｔｈｅｃｈａｒａｃｔｅｒｓｏｆｍｅｔａｌｓ (ｌｕｓｔｅｒ,ｃｏｎｄｕｃｔｉｖｉ ｔｙ ,ｅｔｃ) .Ｔｈｅｙｈａｖｅｅｘｔｒａｏｒｄｉｎａｒｙｈａｒｄｎｅｓｓ ,ｅｘｃｅｌ ｌｅｎｔｒｅｓｉｓｔａｎｃｅｔｏａｂｒａｓｉｏｎａｎｄｅｒｏｓｉｏｎ ,ｓｏｔｈｅｙａｒｅｖｅｒｙｕｓｅｆｕｌｎｏｎ ｏｘｉｄｅｃｅｒａｍｉｃ .Ｔｈｅｙａｒｅｏｆｔｅｎｕｔｉｌｉｚｅｄｔｏｆａｂｒｉｃａｔｅｃｅｒａｍｉｃ …     

纳米晶(Ag-Cu28)-25Sn合金粉末的制备及表征

采用机械合金化法制备纳米晶(Ag-Cu28)-25Sn合金粉末.用X射线衍射(XRD)仪、扫描电镜(SEM)、高分辨透射电镜(HRTEM)和差示扫描量热分析仪(DSC)等分析手段,对合金化过程中物相组成、微观结构及熔化特性进行表征.结果表明:(Ag-Cu28)-25Sn纳米晶合金粉末的物相组成为Cu3Sn和Ag4Sn.球磨 40 h,合金化完全,其熔化温度为548.5 ℃;球磨至60 h,合金明显非晶化,其熔化温度为554.0 ℃,熔程变小且在186.3和399.5 ℃处出现明显放热峰.HRTEM表明,纳米晶的尺寸约为5～10 nm,合金中有非晶态物质出现和晶格缺陷产生.200和400 ℃退火后,合金的平均晶粒尺寸分别为21.3和33.9 nm.     

Microstructure and properties of 2618-Ti heat resistant aluminum alloy

1　INTRODUCTIONAluminumalloy 2 6 18isaheat treatableAl Cu Mg Fe Niforgingalloywhichiswidelyusedinair craftenginecomponentsandautomobileindustries[1] .ItisaheatresistantstructurematerialfabricatedbyI/Mtechnique .TheadditionofsmallamountofFeandNiproducesmicrostructuralstabilityunderther malexposure .Themain precipitatesarecoherentGuinier Preston Bagaryatskii (GPB )zoneswhichformrapidlyonagingattemperaturesuptoatleast2 0 0℃andsemi coherentS′(Al2 CuMg) phasewhichcanapparentlystrength…