高能球磨法制备Fe_3Si合金粉末

采用高能球磨法研究了原子配比Fe75Si25的混合粉末在不同的球磨条件下的机械合金化,用X射线衍射(XRD)仪、扫描电子显微镜(SEM)表征样品的物相、晶体结构、晶粒尺寸和点阵常数,分析了Fe75Si25粉末的机械合金化机理。研究表明,球磨时间、球料比和球磨机转速对机械合金化(MA)进程有重要影响。MA 55h后可达到完全合金化,Si溶入Fe中形成α-Fe(Si)饱和固溶体,晶粒尺寸减小至7～8nm。     

球磨参数对ODS奥氏体不锈钢机械合金化效果的影响

为了研究球磨参数对ODS奥氏体不锈钢机械合金化效果的影响,以Fe、Cr、Ni、W、Ti纯金属元素粉末和纳米Y2O3为原料进行混合(配比为Fe-18Cr-8Ni-2W-1Ti-0.35Y2O3,质量分数),通过高能球磨的方式实现混合粉末的机械合金化.研究球磨时间、转速的变化对粉末粒度、成分均匀度和固溶程度的影响.结果表明,在真空环境下,球料比为10∶1、转速为380r/min、球磨时间60h时,粉末达到了很好的机械合金化效果,成分分布均匀;当球磨时间延长到100h时,粉末颗粒达到最细,继续球磨,粉末将出现明显的团聚.对最优机械合金化工艺参数获得的粉末进行热压致密化研究表明,随着温度的升高,试样的密度随之升高,维氏硬度随之降低.     

过程控制剂对机械合金化Fe-48Al粉末特性的影响

研究了过程控制剂(PCA)-无水乙醇和硬脂酸对机械合金化Fe-48Al(Al原子分数为48%,下同)粉末特性的影响.利用激光粒度仪、扫描电镜和X射线衍射仪分别研究了球磨粉末的粒度、形貌和热处理前后物相结构的变化规律.结果表明,以无水乙醇作PCA时,Fe-48Al的机械合金化速度较快,粉末粒度较小呈不规则薄片状;以硬脂酸作PCA则有利于球磨粉末形态向厚片状或近球形转化.两种粉末经12h球磨后,仍保持固溶体结构;经1100℃真空热处理后,两者均可转变为FeAl(B2)金属间化合物,但无水乙醇作PCA的球磨粉末中Al2O3生成量相对较多.     

球磨合成Fe3Al金属间化合物及其固相反应机理

Fe3Al金属间化合物是一种新型耐高温材料,并因其电热和磁性能受到重视。本文研究由铁、铝元素混合粉末利用高能球磨工艺合成Fe3Al。通过对冷焊现象的分析,用适量的有机物有效地控制了机械合金化过程。利用X射线衍射研究了反应物在球磨过程中的结构演变。通过对Fe／Al固相反应热力学的分析,认为Fe／Al原子比相等成分附近,固相反应最容易进行。     

Al—Fe—V—Si（Nd）合金纳米晶粉末的制备及相转变的研究

利用机械合金化方法制备Al-Fe-V-Si(Nd)合金粉末,球磨状态下得到合金粉末由铝固溶体组成,经适当的热处理后,得到α-A112(Fe,V)2Si粒子弥散分布的合金末,加入稀土后,合金粉末的组织得到细化,并出现非晶化的趋势。利用DNMA方法可以直接得到具有α－Al13(Fe,V)3Si粒子弥散分布的合金粉末,并观察到α－Al13(Fe,V)3Si 转变为准晶的现象,从而证实了准晶相与αAl13(Fe,V)3Si之间的强烈关联性。     

机械合金化法制备Cr掺杂Fe-Si合金

采用高能行星式球磨机制备了Cr掺杂Fe-Si混合粉,用X射线衍射（XRD）测试研究Cr掺杂Fe-Si合金的机械合金化过程,实验结果表明,随着球磨强度的增加,Fe、Cr、Si粉末通过原子扩散实现机械合金化,最佳的球磨工艺参数为：球磨时间35h、球磨机转速360r/min、球料比40：1。     

机械合金化制备Nd60 Fe20 Al10 Co10非晶粉末的研究

利用机械合金化制备Nd60Fe20Al10Co10非晶粉末，采用X射线衍射(XRD)和振动样品磁强计(VSM)研究Nd60Fe20Al10Co10非晶的形成过程、磁性能变化及其与成分结构的关系。结果表明，90min后Al原子溶入Nd原子形成固溶体。球磨2h后出现少量非晶，20h后Co单质和Nd单质消失．组织为非晶相(含少量的α-Fe)。球磨100h最终得到非晶 少量的α-Fe纳米晶。球磨过程中，矫顽力随着合金中非晶的量增加而升高．球磨20h矫顽力达到43kA／m。Nd60Fe20Al10Co10合金具有硬磁性是由于非晶相的存在而造成的。     

机械合金化与放电等离子烧结制备Fe-Fe3Al材料

为开发新型金属材料,采用机械合金化与放电等离子烧结的方法制备Fe-Fe3Al合金.根据Fe-Al二元相图与研究经验,对成分及工艺进行优化设计.用X射线衍射仪(XRD)对成分进行了定性分析,用扫描电子显微镜(SEM)观察了样品的表面与断口形貌,进行了能谱分析,并测试了致密度、显微硬度(HV)及抗弯强度、抗拉强度等力学性能.结果表明:对粉末进行预球磨,并在球磨前后对粉末进行搅拌混合处理,能更好地促使Fe与Al在高能球磨的过程中反应;经放电等离子烧结能够制备出Fe3Al/Fe两相材料,相对密度为99%以上,硬度为HV561,抗弯强度1426 MPa,抗拉强度640 MPa,力学性能优于文献报道的值.     

机械合金化制备NiAl(Cr,Nb)粉体

采用机械合金化的方法制备NiAl(Cr,Nb)金属间化合物粉末。以Ni、Al、Cr和Nb的粉末为原料,按原子分数Ni-38Al-5Nb-5Cr配比,研究其机械合金化过程,并采用XRD,SEM,DSC等分析手段对粉末的结构、颗粒形貌及热稳定性能等进行表征。结果表明:复合粉末在球磨10h后初步合成了NiAl(Cr,Nb),随球磨时间的延长,粉末有细化的趋势,最终产物多为规则的近球形。     

机械合金化法制备电动汽车电机用Fe-Si-Al合金粉

利用机械合金化法制备电动汽车电机用Fe-Si-Al合金磁粉;采用X射线衍射分析和扫描电子显微镜分别表征机械合金化过程中合金粉体的相结构和形貌,采用热分析对合金粉体的稳定性进行分析。结果表明:按照(FeSi)_(75)Al_(25)的原子比进行配料合金粉体,球磨10 h生成纳米晶α-Fe(Al,Si)固溶体,为体心立方晶体结构,粒径为1~20μm;球磨15 h,颗粒不断细化,晶粒粒径可达30 nm;(FeSi)_(75)Al_(25)磁粉在机械合金化过程中形成了具有典型层状结构且表面各种元素均匀分布的合金粉末包覆薄膜,无非晶相生成。     

Formaton of nanocrystalline Mg2Si and Mg2Si dispersion strengthened Mg-Al alloy by mechanical alloying

Formation of Mg₂Si via mechanical alloying of elemental Mg and Si powders has been investigated. The formation of Mg₂Si occurs after 10 hours of mechanical alloying. Nanocrystalline structure of Mg₂Si with grain size of 22 nm obtained after 50 hours of milling was found to be stable upon heating to about 390 °C. Sudden increase in crystalline size to 157 nm after annealing at 520 °C was observed. Although the reaction between Mg and Si could be completed after about 50 hours of mechanical alloying, thermal assisted reaction starting at as low as 190 °C could promote the formation of Mg₂Si at a short milling duration and hence reduce Fe contamination. Mg-Al alloy reinforced by Mg₂Si was prepared by milling Mg, Si and Al powders. Intermediate phase of Al₁₂Mg₁₇ has been detected after 5 hours of mechanical alloying. This intermediate phase was observed to disappear to form equilibrium solid solution of Mg-Al alloy after annealing at 300 °C.     

Nanocrystalline Al/Al12(Fe,V)3Si alloy prepared by mechanical alloying: Synthesis and thermodynamic analysis

Al–Al₁₂(Fe,V)₃Si nanocrystalline alloy was fabricated by mechanical alloying (MA) of Al–11.6Fe–1.3V–2.3Si (wt.%) powder mixture followed by a suitable subsequent annealing process. Structural changes of powder particles during the MA were investigated by X-ray diffraction (XRD). Microstructure of powder particles were characterized using scanning electron microscopy (SEM). Differential scanning calorimeter (DSC) was used to study thermal behavior of the as-milled product. A thermodynamic analysis of the process was performed using the extended Miedema model. This analysis showed that in the Al–11.6Fe–1.3V–2.3Si powder mixture, the thermodynamic driving force for solid solution formation is greater than that for amorphous phase formation. XRD results showed that no intermetallic phase is formed by MA alone. Microstructure of the powder after 60 h of MA consisted of a nanostructured Al-based solid solution, with a crystallite size of 19 nm. After annealing of the as-milled powder at 550 °C for 30 min, the Al₁₂(Fe,V)₃Si intermetallic phase precipitated in the Al matrix. The final alloy obtained by MA and subsequent annealing had a crystallite size of 49 nm and showed a high microhardness value of 249 HV which is higher than that reported for similar alloy obtained by melt spinning and subsequent milling.     

The effect of Ti addition on alloying and formation of nanocrystalline structure in Fe–Al system

In this work, the effect of Ti addition on alloying and formation of nanocrystalline structure in Fe–Al system was studied by utilizing mechanical alloying (MA) process. Structural and morphological evolutions of powder particles were studied by X-ray diffractometry, microhardness measurements, and scanning electron microscopy. In both Fe₇₅Al₂₅ and Fe₅₀Al₂₅Ti₂₅ systems MA led to the formation of Fe-based solid solution which transformed to the corresponding intermetallic compounds after longer milling times. The results indicated that the Ti addition in Fe–Al system affects the phase transition during mechanical alloying, the final crystallite size, the mean powder particle size, the hardness value and ordering of DO₃ structure after annealing. The crystallite size of Fe₃Al and (Fe,Ti)₃Al phases after 100 h of milling time were 35 and 12 nm, respectively. The Fe₃Al intermetallic compound exhibited the hardness value of 700 Hv which is significantly smaller than 1050 Hv obtained for (Fe,Ti)₃Al intermetallic compound.     

Synthesis and structural characterization of nanocrystalline (Ni,Fe)3Al intermetallic compound prepared by mechanical alloying

Synthesis of (Ni, Fe)₃Al intermetallic compound by mechanical alloying (MA) of Ni, Fe and Al elemental powder mixtures with composition Ni₅₀Fe₂₅Al₂₅ was successfully investigated. The effects of Fe-substitution in Ni₃Al alloy on mechanical alloying process and on the final products were investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry, scanning electron microscopy and microhardness measurements. At the early stages, mechanical alloying resulted in a Ni (Al, Fe) solid solution with a layered nanocrystalline structure consisting of cold welded Ni, Al and Fe layers. By continued milling, this structure transformed to the disordered (Ni, Fe)₃Al intermetallic compound which increased the degree of L1₂ ordering upon heating. In comparison to Ni–Al system, Ni (Al, Fe) solid solution formed at longer milling times. Meanwhile, the substitution of Fe in Ni₃Al alloy delayed the formation of Ni (Al, Fe) solid solution and (Ni, Fe)₃Al intermetallic compound. The microhardness for (Ni, Fe)₃Al phase produced after 80 h milling was measured to be about 1170HV which is due to formation of nanocrystalline (Ni, Fe)₃Al intermetallic compound.     

机械合金化-热压烧结制备金属间化合物Fe_3Si

采用机械合金化(MA)和真空热压烧结(HP)法制备金属间化合物Fe3Si。X射线衍射(XRD)、扫描电镜(SEM)、差热分析(DTA)和振动样品磁强计(VSM)分别用于分析化合物的物相、显微形貌、致密度和磁学性质。研究表明球磨55h可达到完全合金化,Si溶入Fe中形成饱和固溶体α-Fe(Si),晶粒尺寸约7～8nm。热压烧结后,α-Fe(Si)固溶体发生有序转变生成Fe3Si。磁性能测量表明:样品的矫顽力随烧结温度的升高而减小;随烧结时间的延长而减小;饱和磁化强度随烧结时间的延长而增大。     

Synthesis, characterization and annealing of mechanically alloyed nanostructured FeAl powder

Elemental powders of Fe and Al were mechanically alloyed using a high energy rate ball mill. A nanostructure disordered Fe(Al) solid solution was formed at an early stage. After 28 h of milling, it was found that the Fe(Al) solid solution was transformed into an ordered FeAl phase. During the entire ball milling process, the elemental phase co-existed with the alloyed phase. Ball milling was performed under toluene to minimise atmospheric contamination. Ball milled powders were subsequently annealed to induce more ordering. Phase transformation and structural changes during mechanical alloying (MEA) and subsequent annealing were investigated by X-ray diffraction (XRD). Scanning electron microscope (SEM) was employed to examine the morphology of the powders and to measure the powder particle size. Energy dispersive spectroscopy (EDS) was utilised to examine the composition of mechanically alloyed powder particles. XRD and EDS were also employed to examine the atmospheric and milling media contamination. Phase transformation at elevated temperatures was examined by differential scanning calorimeter (DSC). The crystallite size obtained after 28 h of milling time was around 18 nm. Ordering was characterised by small reduction in crystallite size while large reduction was observed during disordering. Micro hardness was influenced by Crystallite size and structural transformation.     

Fabrication of Al–Si coating on Ti–6Al–4V substrate by mechanical alloying

Al–Si coatings were synthesized on Ti–6Al–4V alloy substrate by mechanical alloying with Al–Si powder mixture. The as-prepared coatings had composite structures. The effects of Al–Si ratio, milling duration and rotational speed on the microstructure and oxidation behavior of coating were investigated. The results showed that the continuity and the anti-oxidation properties of the coating were enhanced with the increase of Al–Si weight ratio. The thickness of the coating largely increased in the initial 5-hour milling process and decreased with further milling. A rather long-time ball milling could result in the generation of microdefects in coating, which had an adverse effect on the oxidation resistance of coating. Both the thickness and the roughness of the coating increased with the raise of rotational speed. The low rotational speed would lead to the formation of discontinuous coating. The rotational speed had a limited effect on the coating oxidation behavior. Dense, continuous and high-temperature protective Al–Si coatings could be obtained by mechanical alloying with Al–33.3?wt.%Si powder at the rotational speed ranging from 250 to 350?rpm for 5?h.     

Elemental effect on formation of solid solution phase in CoCrFeNiX and CoCuFeNiX (X = Ti,Zn, Si,Al) high entropy alloys

The paper aims to investigate the effect of elements addition, its enthalpy of mixing, crystal structure and atomic size difference on the formation of solid solution phase during the synthesis of high entropy alloy (HEA) by mechanical alloying. For this CoCrFeNiX and CoCuFeNiX (where X?=?Ti, Zn, Si, Al), alloys were prepared by mechanical alloying. The phases formed during mechanical alloying were characterised by X-ray diffraction analysis, transmission electron microscopy and differential scanning calorimetry. Titanium and Aluminium addition facilitate solid solution formation during mechanical alloying. Formation of a BCC and FCC solid solution phase was observed for CoCrFeNiX and CoCuFeNiX system (where X?=?Ti, Al), respectively. Single solid solution phase was not observed for CoCrFeNiZn, CoCrFeNiSi, CoCuFeNiZn and CoCuFeNiSi HEA up to 20?hours of milling.     

高能球磨时间和退火温度对制备TiNi合金粉的影响

为获得高能球磨时间和退火温度对TiNi机械合金粉特性的影响机制,采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱仪(EDS)、差示扫描量热法(DSC)等分析方法对TiNi合金粉进行了研究。结果表明,机械合金的相成分随着在氩气保护气氛中的球磨时间和退火温度的不同而发生变化。球磨22h的产物是非晶态TiNi合金、Ti的固溶体、Ni的固溶体,球磨27h的产物是非晶态TiNi合金粉和Ni固溶体相,球磨30h发生了明显的固相反应,生成了TiNi、Ni3Ti、Ti3Ni4等物相;在650℃/5h和1000℃/5h下的退火产物都是Ni3Ti、Ti2Ni、TiNi2、TiNi和TiC,但在上述2个退火温度下TiNi并不是主要物相,其中在650℃退火时TiNi的含量明显更低。