Effects of ball milling time on porous Ti–3Ag alloy and its apatite-inducing abilities

Ti and Ag powders were mixed with different ball milling time (1, 2, 5 and 10 h) and sintered into porous Ti–3Ag alloys. The samples were treated with hydrothermal treatment, and their apatite-inducing abilities were further evaluated by immersion in modified simulated body fluid. The results indicate that the high surface energy brought by powder refinement leads to the decline of Ag, but promotes the oxidation of Ti during the sintering process. Meanwhile, the hydrothermal treated porous Ti–3Ag alloys prepared by the powders ball milled for 10 h possess the best apatite-inducing ability.     

Mechanical alloying behavior of Nb–Ti–Si-based alloy made from elemental powders by ball milling process

Nb-Ti-Si-based alloy powders were prepared by mechanical alloying(MA) of elemental particles.The evolutions of morphology,size,phase constituents,crystallite size,lattice strain,composition and internal microstructure,etc.,of the alloy powders were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS),laser particle size analyzer and transmission electron microscope(TEM) analyses.The alloy particles are gradually refined and their shapes become globular with the increase in milling time.The diffraction peaks of Nb solid solution(Nbss) phase shift toward lower29 angles during ball milling from 2 to 5 h,and after that Nbss diffraction peaks shift toward higher 29 angles with the increase in milling time from 5 to 70 h,which is mainly attributed to the alteration of the lattice parameter of Nbss powders due to the solution of the alloying element atoms into Nb lattice to form Nbss.During ball milling process,the decrease in crystallite size and increase in lattice strain of Nbss powders lead to continuous broadening of their diffraction peaks.A typical lamellar microstructure is formed inside the powder particles after ball milling for 5 h and becomes more refined and homogenized with the increase in milling time.After 40-h-ball milling,the typical lamellar microstructure disappears and a very homogeneous microstructure is formed instead.This homogeneous microstructure is proved to be composed of only supersaturated Nbss phase.     

机械合金化法制备金锡合金

采用高能球磨机械合金化法制备了Au-20%Sn合金,分析了合金物相、组织和硬度随球磨时间的变化规律,探讨了合金塑性与合金组织及制备工艺的关系。结果表明:采用高能球磨机械合金化法可以制备Au-20%Sn合金;随球磨时间的增加,Au-20%Sn的合金化程度增加,组织中的金属间化合物逐渐增多,最终基本上为δ相和ζ′相;合金的硬度随球磨时间的延长逐渐升高,并在球磨60min后获得最高硬度104.2HV,然后开始下降;球磨后的合金粉末在190℃×2h的烧结过程中发生了不同程度的再结晶和晶粒长大,再结晶程度随球磨时间的延长而增加,导致烧结后合金硬度在球磨时间超过60min后反而下降。     

高能球磨对TiC钢结硬质合金孔隙度影响的研究

采用行星式球磨机对Fe-3.0Cr-3.0Mo-0.5Cu-0.5C-33TiC新型钢结硬质合金混合粉末进行高能球磨,对不同球磨时间粉末形貌及烧结后的合金组织进行观察,测定了烧结后合金的孔隙度。结果表明:球磨初期,粉末粒度迅速减小,粉末出现片状形貌,随着球磨时间增加,粉末粒度减小速度变缓,最后趋于稳定,片状形貌逐渐消失,不规则球形形貌颗粒增多。球磨过程中,在一定时间内,随着球磨时间的增加,混合粉末成分均匀性增加,合金组织细化,孔隙度显著降低。     

Study of the feasibility of producing Al–Ni intermetallic compounds by mechanical alloying

Mechanical alloying (MA) was employed to synthesize Al–Zn–Mg–Cu alloys of high weight percentage of the nickel component from the elemental powders of constituents via high-energy ball milling. The mixed powders underwent 15 h of milling time at 350 rpm speed and 10: 1 balls/powder weight ratio. The samples were cold-compacted and sintered thereafter. The sintered compacts underwent homogenization treatments at various temperatures conditions and were aged at 120°C for 24 h (T6). The milled powders and heat-treated Al alloy products were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The crystallite sizes and microstrains of the alloyed powder were estimated via measuring the broadening of XRD peaks using the Williamson–Hall equation. The results have revealed that optimum MA time of 15 h has led to the formation of Al-based solid solutions of Zn, Mg, Cu, and Ni. The outcomes showed that the Vickers hardness of the sintered Al–Zn–Mg–Cu compacts of Ni alloys was enhanced following aging at T6 tempering treatments. Higher compression strength of Al-alloys with the addition of 15% nickel was obtained next to the aging treatment.     

机械合金化对Cr-W粉末及烧结材料组织的影响

通过机械球磨法制备原子比为4:1的Cr-W预合金粉末,对球磨后的Cr-W粉末进行XRD、SEM、TEM分析,探讨球磨时间对Cr-W粉末形貌、晶粒大小、组织结构及烧结Cr-W合金固溶度的影响。结果表明：采用机械合金化法,可以制备纳米级的Cr-W预合金粉末;球磨初期,晶粒尺寸、微应变变化较大,48 h后趋于稳定获得小于30 nm的纳米晶粉末;经72 h球磨后,粉末中有固溶体形成;球磨过程伴随着晶格常数的变化;球磨时间越长的粉末,烧结后各相分布越均匀,固溶程度越高     

Fabrication and mechanical properties of high-performance aluminum alloy

High-performance Al–Cu–Mg alloy was fabricated by high-energy ball milling, sintering, and hot extrusion. The microstructure and mechanical properties of the material were preliminarily investigated. Results show that the formation of liquid phase during sintering promotes the densification of the aluminum powders. A97.1 % theoretical density is achieved in this alloy after sintering. The material shows excellent mechanical properties after extrusion and heat treatment. The ultimate tensile strength and yield strength of the extruded samples with heat treatment are 613 and 465 MPa, respectively.     

Effect of ball milling conditions on the microstructure and the transformation behavior of Ti−Ni and Ti−Ni−Cu shape memory alloy powders

Ti−50Ni and Ti−40Ni−10Cu (at.%) shape memory alloy poweders have been fabricated by the ball milling method. Their alloying behaviour and transformation behaviour were investigated by means of optical microscopy, electron microscopy, X-ray diffractometry and differential scanning calorimetry. As-milled Ti−Ni powders fabricated with a milling time of less than 20 hrs were a mixture of pure elemental Ti and Ni, and therefore we were unable to obtain alloy powders because the combustion reaction between Ti and Ni occurred during heat treatment. Since those fabricated with a milling time of more than 20 hrs were a mixture of Ti-rich and Ni-rich Ti−Ni solid solution, it was possible to obtain alloy powders without a combustion reaction during heat treatment. Clear exothermic and endothermic peaks appeared in the cooling and heating curves, respectively, in DSC curves of 20 hr and 30 hr milled Ti−Ni powders. On the other hand, in DSC curves of 1 hr, 10 hrs, 50 hrs and 100 hrs, the thermal peaks were almost discernible. The optimum ball milling time for fabricating Ti−Ni alloy powders was 30 hrs. Ti−40Ni−10Cu alloy powders were fabricated successfully by the optimum ball milling conditions deduced from Ti−50Ni alloy powders.     

Mechanical alloying characteristic and thermal stability of Al<Subscript>78</Subscript>Fe<Subscript>20</Subscript>Zr<Subscript>2</Subscript> amorphous powders

The powders of pure Al, Fe, and Zr for preparing Al₇₈Fe₂₀Zr₂ were subject to a high-energy planetary ball milling. The microstructure evolution of the mixtures at the different intervals of milling was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). It was found that a nearly complete amorphization could be achieved in the mixtures after ball milling for 23 h. Further ball milling led to the crystallization of the amorphous powders. A long time ball milling, e.g., 160 h, led to a complete crystallization of the amorphous powders and the formation of Al₃Zr and Al1₃Fe₄. The crystallization products caused by ball milling are almost the same as that produced by isothermal annealing of the amorphous powders in vacuum at 800 K for 1 h.     

Al-V合金预磨状态对Al-Fe-V-Si-Nd机械合金化过程中显微组织演化的影响

采用高能球磨法制备Al89.5Fe6 .4V0 .7Si2 .4Nd合金粉末 ,并用X射线衍射技术研究了球磨过程中的组成。发现经 60h高能球磨 ,合金粉末的微观组织由Al非晶和Al3V相组成 ;Al V合金的预磨状态影响Al89.5Fe6 .4 V0 .7Si2 .4Nd合金机械合金化过程中显微组织演化。     

细晶TiAl基合金的制备及高温氧化行为

采用机械合金化及放电等离子烧结方法制备超细晶/纳米晶TiAl基合金,并利用差热分析仪进行循环高温氧化试验,研究粉末机械合金化对烧结细晶粒TiAl基合金组织及高温氧化性能的影响。结果表明,球磨是获得细晶粒组织的原因,粉末经球磨及放电等离子烧结后,形成了细小、球状的TiAl和Ti3Al相组织;该细晶粒组织在高温循环氧化条件下显示出较高的抗氧化性,且随Nb量增加抗氧化性得到提高,升温阶段的氧化速率最快。     

机械球磨Ag-Zn合金粉末显微组织及内氧化性能

利用XRD、SEM研究球磨时间对Ag-Zn合金粉末显微组织和内氧化性能的影响。结果表明:球磨初期,晶粒尺寸迅速减小,微观应变急剧增加,球磨25h后,变化趋于平缓,球磨100h后,晶粒尺寸和微观应变分别为20nm和0.55%。Ag-Zn合金粉末在机械球磨过程中经历了片层化、片层结构破裂细化、破裂和冷焊的平衡阶段以及片层组织焊合成团4个阶段。Ag-Zn合金粉末的内氧化速度随球磨时间延长而增加,球磨100h的粉末在0.5h内即达到最大氧化程度,与未球磨粉末相比提高了25%。Ag-Zn合金粉末在内氧化过程中,未球磨粉末样品中ZnO呈针状和片状形成于表面且尺寸较大;粉末经机械球磨后氧化,ZnO则主要以针状形式存在于基体中,尺寸较小。生成ZnO产生的体积膨胀,在内氧化区形成压应力,导致银原子向粉末表面扩散形成银球。     

Effect of ball milling parameters on the microstructure of W–Y powders and sintered samples

High energy milling carried out in a planetary ball mill was used in order to alloy elemental powders and to obtain nanostructures and oxide dispersion strengthened (ODS) alloys. Owing to such advantages, this process was retained so as to elaborate ODS tungsten alloys from tungsten and yttrium powders by using a WC–Co milling system with 16 balls. The experiments were performed for a duration of up to three days while applying a 400 rpm speed and a ball-to-powder weight ratio of 16. The W–1 vol%Y blends were subsequently compacted at room temperature and sintered at 1800 °C for 4 h. The present paper deals with the effect of milling time on the mechanical behavior of the powders, on the refinement of the microstructure, on the improvement of the second phases distribution and on the contamination by cobalt, carbon and oxygen. At last, these results are related with the behavior of the powders during densification.     

高能球磨工艺对Ti50Ni22Cu25Sn3组织演变的影响

用高能球磨法制备Ti50Ni22Cu25Sn3非晶粉末,并研究球磨工艺参数对Ti50Ni22Cu25Sn3非晶形成过程的影响。结果表明,球磨转速以及磨球直径对Ti50Ni22Cu25Sn3非晶相的形成效率具有十分重要的影响。较高的转速和合适的球径能有效促进该Ti基合金的非晶化,缩短合金非晶化的时间,当转速为400 r/min,球料比为20:1时,球磨时间约为30 h后,可得到完全的Ti50Ni22Cu25Sn3非晶粉末     

高能球磨对AgSnO_2电触头材料组织与性能的影响

对雾化法制备的AgSnO2粉末进行球磨处理,研究了高能球磨对AgSnO2粉末的形貌及其烧结性能的影响。结果表明:高能球磨有利于提高AgSnO2粉末的烧结性能,改善烧结坯的显微组织以及第二相粒子SnO2在Ag基体中的分布,因而获得了晶粒细小、致密度高、抗弯强度大以及加工性能优良的AgSnO2电触头材料。     

纳米AgSnO2触头材料的制备与组织分析

利用高能球磨技术制备纳米AgSnO2粉末，热压烧结后，制得纳米AgSnO2块体，与传统内氧化法制得的AgSnO2InO3比较表明，高能球磨法能够克服内氧化法氧化物的聚集及晶界处析出的缺陷，得到SnO2均匀分布于Ag基体上的组织结构。     

机械合金化制备Ni-B-Si合金粉末

本实验选取成分为92%Ni-4%B-4%Si的混合粉末进行机械合金化,并每隔一定时间定量取粉进行SEM、XRD及DSC分析。实验结果表明,当球磨至30 h时,粉末形貌趋于球状,微量元素B和Si已经完全向镍中固溶,此时起始熔化温度降至1038℃;继续延长球磨时间粉末发生团聚,并在球磨至80 h时,趋于非晶化转变;将球磨40 h的合金粉末与松装镍粉在1100℃进行熔渗烧结时,发现其与镍粉发生冶金结合并形成致密的烧结体。     

Development of nano-structure Cu-Zr alloys by the mechanical alloying process

Cu-Zr alloys have many applications in electrical and welding industries for their high strength and high electrical and thermal conductivities. These alloys are among age-hardenable alloys with capability of having nano-structure with high solute contents obtainable by the mechanical alloying process. In the present work, Cu-Zr alloys have been developed by the mechanical alloying process. Pure copper powders with different amounts of 1, 3 and 6 wt% of commercial pure zirconium powders were mixed. The powder mixtures were milled in a planetary ball mill for different milling times of 4, 12, 48 and 96 h. Ball mill velocity was 250 rpm and ball to powder weight ratio was 10:1. Ethanol was used as process control agent (PCA). The milling atmosphere was protected by argon gas to prevent the oxidation of powders. The milled powders were analysed by XRD technique and were also investigated by SEM observations. Lattice parameters, crystal sizes and internal strains were calculated using XRD data and Williamson-Hall equation. Results showed that the lattice parameter of copper increased with increasing milling time. The microstructure of milled powder particles became finer at longer milling time towards nano-scale structure. SEM observations showed that powder particles took plate-like shapes. Their average size increased initially and reached a maximum value then it decreased at longer milling times. Different zirconium contents had interesting effects on the behavior of powder mixtures during milling.     

Two milling time regimes in the evolution of magnetic anisotropy of mechanically alloyed soft magnetic powders

The milling time evolution of magnetic anisotropy of ball milled powders can be described considering two regimes. First, for short milling times, the main factor affecting the magnetic behavior of the alloy is the accumulation of internal stresses. Second, for long milling times, magnetic anisotropy can be explained using three contributions: long-range magnetoelastic, averaged short-range magnetoelastic and averaged magnetocrystalline anisotropies.     

Relationship between powder characteristic and internal oxidation of AI in Cu-AI pre-alloyed powders

Since Cu-AI powder characteristics have important effects on the preparation of Cu/AI203 composite, the apparent activation energy of Al internal oxidation reac-tion in Cu-AI pre-alloyed powders with different characteristics was calculated in the present investigation. The microstructure and properties of the synthesized Cu/AI2O3were studied. The results show that high-energy milling can obviously promote in-ternal oxidation of AI in Cu-AI powders in the same solid solubility. At the same milling conditions and internal oxidation parameters, the solid solution of AI in Cu either in low or high amount will result in the poor microstructure and properties of the Cu/AI2O3 composite. Subsequently, when high-energy milling and internal oxidation are synchronously used to prepare the Cu/AI2O3 composite, there should be an appropriate solubility and milling effect for the pre-alloyed powders.