Mechanical alloying of Mo—Si—Fe powders

Mechanical milling behavior of Mo-Si-Fe powders was investigated u sing XRD, SEM and TEM techniques. The mixtures of elemental molybdenum (>99%), s ilicon (>99%) and iron (>98%) powders with a stoichiometry of Mo5-xFe xSi3 (x=0.5, 1, 2) were milled in a planetary mill for up to 195 h. For all three powder mixt ures, high-energy milling of 60h led to formation of the Mo(Fe, Si) supers aturated solid solution (Moss); and to a remarkable expansion of the solub ility of Fe, Si in molybdenum. The transformation of Moss to an amorphous phase was identified after longer time milling. In the milling process, the grain size of Mo (Fe, Si) decreased gradually and the internal stress increased linearly. After 40 h milling, the grain size was reduced to about 11 nm. SEM analysis of milled powders showed that the particle size increased initially with milling time. After 195 h milling, particles exhibited a spherical morphology and the particle size were reduced to about 100 nm.     

Cu-Al-B2O3-TiO2粉末机械合金化

利用XRD ,SEM和DTA等方法分析了Cu Al B2 O3 TiO2 粉末在机械合金化过程中的结构变化。结果表明 :Cu Al B2 O3 TiO2 粉末通过机械合金化可以形成Cu(Ti,B)及Al2 O3 和少量的TiCu3 粉末 ,Al2 O3 是通过机械合金化过程中局部的自维持反应形成的 ,并且有 6～ 12h的孕育期。在所研究的体系中 ,先产生 4Al 3TiO2 =3Ti 2Al2 O3 的自维持反应 ,此反应诱发了随后的 2Al B2 O3 =2B Al2 O3 自维持反应。球磨过程中局部的自维持反应与普通的自蔓延反应有相似的一面 ,其不同点主要是点燃温度低 ,点燃位置多。     

75％TiO2-25％SiO2氧化物的机械合金化

金红石TiO2是常用的钛阳极耐蚀载体材料。鉴于SiO2具有更高的耐蚀性、耐磨性和稳定性，而且价格低廉。因此，本文尝试以锐钛矿TiO2和石英SiO2颗粒原料，采用机械合金化（MA）方法制备TiO2-SiO2二元氧化物。本文通过30小时机械合金化作用，制备了摩尔浓度为75％TiO2-25％SiO2二元氧化物载体材料。通过XRD、DTA和TEM分析并观测了所获材料的组织结构和晶粒形貌。结果发现在MA作用下，该载体材料中的锐钛矿TiO2显著细化，有部分纳米晶粒出现，SiO2晶粒细化效果相对较弱；透射电镜下，粉末颗粒呈理想的等轴形态；产生了锐钛矿TiO2向金红石TiO2的相变，其相变温度比采用常规方法下的相变温度明显降低了约350℃：获得SiO2、TiO2互溶的固溶体组织，特别是生成了采用常规方法难以获得的TiO2．SiO2非平衡间隙固溶体。     

Fabrication of high strength conductivity submicroncrystalline Cu-5 % Cr alloy by mechanical alloying

1　ＩＮＴＲＯＤＵＣＴＩＯＮＣｏｐｐｅｒａｌｌｏｙｓｗｉｔｈｈｉｇｈｓｔｒｅｎｇｔｈａｎｄｈｉｇｈｅｌｅｃ ｔｒｉｃａｌｃｏｎｄｕｃｔｉｖｉｔｙａｒｅｇａｉｎｉｎｇｉｎｃｒｅａｓｉｎｇｉｎｔｅｒｅｓｔｄｕｅｔｏｔｈｅｉｒｗｉｄｅａｐｐｌｉｃａｔｉｏｎｂａｃｋｇｒｏｕｎｄａｓｖａｒｉｏｕｓｅｌｅｃ ｔｒｏｄｅｍａｔｅｒｉａｌｓ[1,2 ] .Ｔｈｅｓｅａｌｌｏｙｓａｒｅｎｏｒｍａｌｌｙｐｒｅ ｃｉｐｉｔａｔｉｏｎｏｒｄｉｓｐｅｒｓｉｏｎｈａｒｄｅｎｅｄａｌｌｏｙｓｂｅｃａｕｓｅａｌｔｅｒ ｎａｔｉｖｅｌｙｓｔ…     

Ti／Al二元粉末的机械合金化

采用自制球磨机机械合金化Ti/Al二元粉末,研究了机械合金过程中粉末结构的变化。结果表明：Ti50Al50混合粉径高能球磨后,颗粒尺寸迅速增大,而后快速下降,Ti,Al晶粒各自逐渐细化至纳米尺寸,进一步球磨,颗粒尺寸减小甚微,晶粒尺寸进一步细化导致形非晶,但在此过程中并没有发现Ti-Al金属间化合物的形成;随球磨时间的延长,粉末显微硬度开始略有下降,然后迅速增加,在基本形成非晶后,保持恒定值。     

机械合金化法制备不同Cr含量的W-Cr纳米合金粉末

采用机械合金化法制备Cr含量为8%、12.5%、20%（质量分数）的纳米W-Cr合金粉,对不同球磨时间粉末进行X射线衍射分析,以确定物相、晶粒尺寸及微应变,并采用扫描电子显微镜观察粉末形貌及粒度的变化。结果表明,采用机械合金化法可以制备不同Cr含量的纳米W-Cr合金粉。随着Cr含量的增加,制备纳米W-Cr合金粉所需球磨时间越长,其中W-8%Cr、W-12.5%Cr和W-20%Cr粉末的最佳球磨时间分别为72、84和96 h,晶粒尺寸小于30 nm。随着球磨时间的增加,晶粒尺寸不断减小,微应变逐渐增加,使常温下Cr在W中的固溶度增加,形成W的过饱和固溶体。Cr含量不同的W-Cr粉末完全合金化均经过4个阶段。     

铜锌粉末低温机械合金化

对铜锌粉末在-30℃、-20℃以及常温条件下进行了高能球磨.利用透射电镜、X射线衍射仪对粉末的微观形貌、显微结构、晶体结构进行了研究.结果表明:-30℃低温可显著降低粉末塑性,不添加过程控制剂时,球磨过程可顺利进行,颗粒表面平整,呈脆性断裂特征;常温与-30℃低温球磨10 h产物均为α γ相.-20℃低温不添加过程控制剂时,冷焊作用强,球磨不能顺利进行;添加过程控制剂后,球磨过程顺利进行,颗粒尺寸最小,-20℃球磨10 h产物为α相、γ相与ZnO,继续球磨,最终形成α相、ZnO及未知相.     

Synthesis of TiB_2 TiC by mechanical alloying

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

Mechanical properties of injection molded Fe-6% Ni-0.4% C steels with varying Mo contents of 0.5 to 2%

In our previous studies, sintered and heat-treated alloy steels (Fe−6Ni−0.5Mo−0.4C (mass%)) produced by a MIM process showed excellent mechanical properties of 2000 MPa tensile strength and 5% elongation. This was attributed to the solid solution strengthening and the mezzo-heterogenous microstruture, which consisted of martensite or retained austenite (Ni and Mo rich phases) surrounded by a network of tempered martensite. This study has been performed to clarify the effect of Mo on the mezzo-heterogeneous microstructure and the mechanical properties of MIM processed and sintered alloy steels (Fe−6Ni−0.4C) with varying Mo content (0.5–2 mass%). The tensile properties of the heat-treated steels with added 2 mass% Mo were lower than those of the steels with added 0.5 mass% Mo. The reduction in the tensile properties, particularly the appearance of large pores formed at the original location of Mo power through the transient liquid phase formation and the low hardness of the matrix, was due to the low sintered density. By using mechanically milled fine Ni and Mo powders, the heat-treated steel (Fe−6Ni−2Mo−0.4C) showed excellent properties, including tensile strength of 1800 MPa and ductility of 2.2% elongation. This article is based on a presentation made in the symposium “The 3rd KIM-JIM Joint Symposium on Advanced Powder Materials”, held at Korea University, Seoul, Korea, October 26–27, 2001 under auspices of The Korean Institute of Metals and Materials and The Japan Institute of Metals.     

LaNi5-Mg合金的机械合金化合成与表征

采用机械合金化合成了新型合金LaNi5—38％Mg(质量分数，下同)，并采用X射线衍射(XRD)，扫描电子显微镜(SEM)，差热分析(DTA)等对其结构、形貌及热稳定性能等进行了表征。结果表明：经280r／min球磨250h后，LaNi5—38％Mg合金由非晶和MgNi2纳米晶(5．4nm)组成：所得粉末大多数为规则的近球形或球形，另有少量的多角形或梨形，其粒径为0．05μm～13．9μm，其中90％的颗粒为0．5μm～2．0μm。球磨试样经763K保温35d，获得了热稳定性较好的具有纳米尺度(25.3nm)的三相合金。     

合金化和形变处理对Cu-Mg-Te-Y合金组织性能的影响

制备具有高强高导性能的铜合金,研究添加Mg和微量的Y对合金的组织和性能的影响。通过变形和退火等工艺处理后,Cu-0.47Mg-0.2Te-0.04Y合金的性能指标可达到：抗拉强度510 MPa,伸长率11%,导电率大于63% IACS。稀土元素Y的熔体净化作用、细晶强化作用和添加适量Mg产生的固溶强化作用能够提高合金的力学性能和导电率。     

Mechanical alloying and characteristics of spark plasma sintering of Ti-A1 composite powders

The mechanical alloying process of Ti-Al composite powders were carried out by use of high energy ball-milling machine. Structure variations of powder mixtures during mechanical alloying and characteristic of spark plasma sintering were investigated. The results show that during milling, TiAl, Ti3Al and Ti2Al phase intermetallic compounds are formed, simultaneously with powder refinement for the （TiH2-45Al-0.2Si-SNb） and （TiH2-45Al-0.2Si-7Nb） mixtures. The particle sizes of two powder mixtures are less than 300 nm after milling for 30 h. Sintering process of the milled powder can be completed in a short time by spark plasma sintering, and the sintering microstructure is composed of fine and homogeneous TiAl and Ti3Al phase.     

机械合金化对Mg_2Ni相形成的影响

用两步法 (即由机械合金化和压制烧结两个步骤组成 )制备了Mg2 Ni合金。实验证明 :混合粉经机械合金化后 ,晶粒细化 ,增加了固态扩散的能力 ,有利于固相反应进行 ,使Mg2 Ni产率明显提高。不同温度烧结处理的结果表明 :烧结温度是影响Mg2 Ni相形成的重要因素 ,烧结温度达到 843K ,Mg Ni粉基本能完全转变为Mg2 Ni相。     

Synthesis of TiB2 nanocrystalline powder by mechanical alloying

1 Introduction TiB2 has been widely used in some industrial fields owing to its high melting temperature, hardness, elastic modulus, electro-conductibility and thermal diffusivity, and excellent refractory properties and chemical inertness. Usually, TiB2…     

Mechanical wet-milling and subsequent consolidation of ultra-fine Al2O3-（ZrO2＋3%Y2O3） bioceramics by using high-frequency induction heat sintering

Alumina/zirconia composites were synthesized by wet-milling technique and rapid consolidation with high frequency induction heat sintering(HFIHS). The starting materials were a mixture of alumina micro-powder (80%, volume fraction) and 3YSZ nano-powders (20%). The mixtures were optimized for good sintering behaviors and mechanical properties. Nano-crystalline grains are obtained after 24 h milling. The nano-structured powder compacts are then processed to full density at different temperatures by HFIHS. Effects of temperature on the mechanical and microstructure properties were studied. Al2O3-3YSZ composites with higher mechanical properties and small grain size are successfully developed at relatively low temperatures through this technique.     

Fabrication of Ti3AIC2 ceramic material by mechanical alloying

Ti3A1C2 has the properties of ceramics and metals. These excellent properties indicate that Ti3A1C2 is a very promising material to extensive applications. Ti3A1C2 ceramic material was prepared by mechanical alloying. The effects of milling time and sintering temperature on the fracture, microstructure and mechanical properties of Ti3A1C2 ceramic material were analyzed by laser particle analyzer, X-ray diffraction,and scanning electron microscopy. The experimental results showed that Ti3A1C2 had the best comprehensive properties after the composite powder was milled for 3 h and sintered at 1630℃ for 2 h. The relative density, bending strength, and hardness of the sample reached 92.23%,345.2 MPa, and HRA 34.1, respectively. The fracture surface indicated that the fracture of the material belonged to ductile rapture.     

合金元素对Cu-Ag合金组织、力学性能和电学性能的影响

采用冷变形及中间热处理方法制备了具有双相纤维复合组织的Cu-Ag合金，研究了成分与组织，性能的关系，随着变形程度的增加，合金强度上升而电导率下降，合金中Ag含量由6％增加至24％时，铸态组织中第二相数量明显增多，变形后能够形成更多的Ag纤维复合相，因而合金强度明显上升，在Cu-6%Ag中添加1％Cr元素可以使合金基体得到进一步强化并在一定程度上细化了Ag纤维相，也可使合金度得到显著改善，在Cu－6%Ag-1%Cr合金中添加微量稀土元素可使Ag纤维分布更为弥散，因而使合金在不降低导电性的同时增加强度，尤其在高强度范围内这种作用更为显著。     

Mg-5Al-10.3Ti纳米复合材料的力学性能及微观组织

通过机械化学研磨法将Mg、Al、Ti粉末混以聚乙烯乙二醇进行研磨,合成了Mg-5Al-10．3Ti纳米复合材料。与常规粉末冶金法相比,该法合成的材料的力学性能呈现出反常的应变软化现象。透射电子显微镜分析表明,合金中镁晶粒尺寸大多为20～30nm,个别晶粒的尺寸约为90nm;此外,观察到许多直径约3～7nm的纳米管。     

Synthesis and grain growth kinetics of in-situ FeAl matrix nanocomposites（ Ⅰ ）： Mechanical alloying of Fe-A1-Ti-B composite powder

Three nanocrystalline alloys, FesoAlso, Fe42.5Al42.5Ti5B10 and Fe35Al35Ti10B20 （molar fraction, %）, were synthesized from elemental powders by high-energy ball milling. The structural evolutions and morphological changes of the milled powders were characterized by X-ray diffractometry（XRD）, transmission electron microscopy（TEM） and scanning electron microscopy（SEM）. The effects of different Ti, B additions on the structure and phase transformation in these alloys were also discussed. It is observed that the diffusion of AI, Ti, B atoms into Fe lattice occurs during milling, leading to the formation of a BCC phase identified as Fe（Al） or Fe（Al, Ti, B） supersaturated solid solution. Fe-based solid solution with nanocrystalline structure is observed to be present as the only phase in all the alloy compositions after milling. Furthermore, the contents of Ti, B affect the formation of mechanical alloying products, changes in the lattice parameter as well as the grain size.