影响铜粉和镍粉界面过程的因素

研究了在铜粉和镍粉反应形成固溶体组织的过程中，影响铜粉和镍粉界面扩散和迁移的因素。结果表明，粉末颗粒均匀、1：1质量配比、采用机械混料、二次温压和快速加压、提高压制压力和烧结温度以及延长保温时间都可以促进反应过程中的界面扩散和迁移。     

铜粉和镍粉反应的试验研究

研究了铜粉和镍粉反应形成单相Cu-Ni固溶体组织的过程和机理及其结构特征。研究发现，在反应过程中，只有镍粉颗粒扩散进入铜粉颗粒，在原铜粉颗粒内部反应形成单相α固溶体组织。铜和镍混合粉在100kN预压、300kN温压，800℃烧结、保温15h工艺条件下反应，全部形成了单相Cu-Ni 固溶体组织。当不同比例的铜粉和镍粉反应形成连续固溶体时，固溶体的点阵常数与成分近似成直线关系。     

C／CuPb复合轴承材料温压成形工艺的研究

用温压工艺制得了短碳纤维增强铜铅合金（Ｃ／ＣｕＰｂ）复合轴承材料,研究了温压工艺参数对温压压坯及烧结坯性能的影响,并对温压烧结与冷压烧结及二次压制烧结所得Ｃ／ＣｕＰｂ复合轴承材料的性能进行了分析对比。结果表明,温压压坯比冷压压坯具有更高的生坯密度,同时,温压烧结Ｃ／ＣｕＰｂ复合轴承材料的性能与二次压制烧结材料相当而明显高于冷压烧结材料。     

微量纳米铜对铁基粉末冶金制品致密性的影响

为提高铁基粉末冶金制品的密度,试验采用高能球磨机在铁基粉末中添加少量不同含量的纳米铜粉体均匀混合,在相同压力750 MPa下压制块状试样,在920℃,保护性气氛下进行烧结,烧结时间6 h.对不同纳米铜含量烧结后的试样进行了密度、显微组织、硬度、TEM、XRD测试.结果表明:随纳米铜含量的提高,材料的密度明显提高.没有添加纳米铜试样烧结后的密度为6.6 g/cm3;添加3%纳米铜的试样烧结后的密度为7.3 g/cm3,显微组织中空隙率显著减少,同时提高了制品硬度.原因是纳米铜粉体在铁基颗粒界面上的作用,提高了材料的致密性.     

不同冷压压力下Fe-Cu基金刚石复合材料超薄切锯胎体的组织和致密化机理

采用单轴模压法,以Fe-Cu基单元素混合粉末为原材料,在不同冷压压力下制备Fe-Cu基金刚石复合材料超薄切锯胎体压坯;利用显微硬度仪、阿基米德原理和OM、SEM表征冷压坯的显微硬度、组织和密度,研究不同压力下冷压坯的致密化机理。结果表明:随着冷压压力的增大,压坯中粉末的变形不均匀,粉末间摩擦力不断发生变化,制约了粉末颗粒的结合方式、显微硬度、排布及胎体密度。     

Cu含量对Fe-Cu-C系粉末冶金轴承材料组织性能的影响

以还原铁粉、电解铜粉、鳞片状石墨粉制备成形的混合料为原料，经压制烧结得到了Fe-xCu-0.7C(x=10、15、20和25 mass%)粉末冶金轴承材料。采用扫描电镜、洛氏硬度计、万能材料试验机及摩擦磨损试验等研究了烧结体试样的显微组织、硬度、压溃强度及摩擦磨损性能，分析了Cu含量对烧结体试样的孔隙率、显微组织和力学性能的影响。结果表明：烧结体试样的显微组织主要由珠光体、铁素体、Cu相以及孔隙组成，随着Cu含量从10%增加到25%,烧结体的开孔隙率和硬度降低，压溃强度先升高后降低，摩擦系数以及体积磨损量先降低后升高。当Cu含量为15 mass%时，Fe-15Cu-0.7C烧结体试样的综合性能较好，其密度、硬度、压溃强度、摩擦系数以及体积磨损量分别为6.14 g/cm³、51.81 HRB、419.96 MPa、0.23和0.2145 mm³。     

合金元素P,Cu含量对铸铁短纤维结合剂组织和性能的影响

本文研究了合金元素磷和铜对铸铁短纤维烧结体显微组织和性能的影响。结果表明，合金元素磷可显著提高铸铁短纤维烧结体的密度、致密化系数和压强度。磷与铜的共同加入可进一步提高烧结体的压溃强度和硬度，同时，铜的加入可抑制由磷引起的烧结体的急剧。烧结机理随磷、铜含量的增加逐渐由固相烧结＋瞬态液烧结转变为液相烧结。     

微细铬铁粉对铁基烧结材料性能的影响

研究了加入微细铬铁粉对Fe-Ni-Mo-Cu系粉末冶金材料烧结性能和力学性能的影响.材料经冷压后于1150℃常规烧结,进行了密度、孔隙及组织观察、表观硬度(HRB)、显微组织硬度和拉伸强度测试,通过扫描电镜观察拉伸断口形貌,分析研究其断裂机理.结果表明:当添加微细粉Cr含量为0.2%～1.5%时,随着Cr含量的增加,材料的烧结密度在7.04～7.08g/cm3之间,表观硬度、显微硬度和拉伸强度逐渐增大,材料属脆性断裂.微细铬铁粉的加入对材料的性能改善效果显著.     

微颗粒制备Cu-Ni二元合金及性能研究

采用铜粉、镍粉粉末为原料,通过机械合金化和热压烧结工艺制备了Cu-Ni合金材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、金相显微镜(OM)等检测手段对粉体的机械合金化过程、合金材料的微观组织特征以及电学性能、力学性能进行了研究与分析。结果表明:Cu-Ni二元粉末机械合金化后XRD测试结果未形成新相,证实二元合金的微观组织中Ni元素已固溶于铜基体中,并出现了孔洞。导电率、致密度和硬度均随着Ni含量的增加而出现了降低。     

原位反应合成AgSnO_2CuO电触头复合材料性能的研究

AgCu、AgSn、AgSnCu、Ag_2O、Ag粉经研磨、烧结和复压复烧等实验过程制备出AgSnO_2CuO复合材料,并研究了该材料的密度、硬度、电阻率以及显微组织。结果表明,以AgCu、AgSn为原料的复合材料组织分布比以AgSnCu为合金原料的均匀,并且弥散程度较高。此外,压坯密度和烧结后样品密度变化不大,且复压复烧可有效提高样品的密度,复压复烧后样品的电阻率比烧结态的低,而硬度有所升高。     

Warm compaction powder metallurgy of Cu

A series of experiments were carried out using different admixed lubricant contents, different compaction pressures and temperatures in order to study the warm compaction of copper powder. Results show that too much admixed lubricant will lead to the squeeze out of the lubricant from the compact during the warm compaction processing of Cu powder. Results also show that blisters can be found in sintered samples that contain lubricant less than 0.15%(mass fraction). Optimal warm compaction parameters for producing high density powder metallurgy copper material are obtained. Compacts with green density of 8.6 g/cm^3 and a sintered density of 8.83 g/cm3 can be produced by warm compacting the Cu powder, which contains 0.2% admixed lubricant, and is compacted at 145℃ with a pressure of 700 MPa.     

Effect of sintering parameters on warm compacted iron-based material

1　INTRODUCTIONItiswellknownthatincreasingdensityisthebestwaytoincreasetheperformanceofpowdermet allurgy(P/M ) parts.ConventionalP/Mprocessingcanproduceiron basedpartswithdensitylessthan 7.1g/cm3(arelativedensityof 90 %approximately) .Theirmechanicalpropertiesaresubstantiallylessthanthoseoftheirfulldensitycounterpart .TherearemanymethodsthatcanproduceP/M partswithrela tivelyhighdensitysuchaswarmcompaction ,hightemperaturesintering ,doublepress/doublesinteringandforging .Warmcompactioni…     

基于有限元模拟的钼粉末温压成形分析

为了研究钼粉末温压成形过程,用有限元分析软件建立了钼粉末温压成形的有限元模型,对三维圆柱等截面粉柱温压成形过程进行了有限元数值模拟,从模拟结果得到了最终坯体内部密度和应力等参量的分布情况以及钼粉末颗粒轴向和径向流动规律.实验验证了所建立有限元模型的可靠性,并分析了部分工艺和材料性能参数对钼粉末成形的影响.结果表明:在钼粉末的温压成形过程中,压坯顶部半端面、轴截面和侧壁的相对密度分布等值线和其应力分布等值线非常接近.     

Microstructure and mechanical properties of Ti6Al4V powder compacts prepared by magnetic pulse compaction

Ti6Al4V powder compaction was performed by using magnetic pulse compaction in air at 200℃.Effects of process parameters such as voltage,capacitance,discharge times on the microstructure,compressive strength,hardness and relative density of compacts were investigated.The experimental results show that the relative density,hardness and compressive strength of compacted specimens increase with increasing voltage.In addition,the relative density and compressive strength of compacted specimens increase with the augmentation of capacitance in the range investigated.The relative density increases,the hardness firstly increases and then tends to be a fixed value;and the compressive strength firstly increases and then decreases from one to five times compaction.Both values of the hardness and compressive strength reach the maxima of HRA 69.1 and 1 062.31 MPa,at three times compaction,respectively.There are pores in and between particles.     

Age Hardening of AlCrMoNiTi High Entropy Alloy Prepared by Powder Metallurgy

采用粉末冶金工艺制备了AlCrMoNiTi高熵合金,并对其铸态和退火态的微观组织和硬度进行了研究。结果表明,铸态合金由富(Cr,Mo)bcc固溶体枝晶相和富(Al,Ni,Ti)fcc固溶体枝晶间相组成。时效合金在900℃高温可获得最高硬度HV约为6150 MPa,在1000℃发生退火软化现象,但是其硬度HV仍保持在5160 MPa的高硬度水平。这表明,AlCrMoNiTi高熵合金具有优异的高温时效硬化特性。该合金在800℃时的时效硬化特性主要归因于细晶强化,在900℃时则归因于第二相(bcc2)的析出硬化。在1000℃时发生退火软化现象,其原因在于第二相的分解和晶粒粗化。     

压扭工艺改善钼粉末温压成形的模拟分析

运用MSC．Marc有限元仿真软件,采用基于更新拉格朗日方法的热-机耦合分析方法,模拟了钼粉温压和温压扭成形过程,获得了2种工艺条件下的粉坯相对密度分布规律,验证了有限元模型的可靠性。结果表明：压扭工艺可以减小粉坯端面边缘处相对密度分布梯度,增大侧壁附近粉末变形量,并显著提高平均相对密度及相对密度分布的均匀性。     

Die wall lubricated warm compacting and sintering behaviors of pre-mixed Fe–Ni–Cu–Mo–C powders

Polytetrafluoroethylene (PTFE) emulsion was used as die wall lubricant. Die wall lubricating warm compacting and sintering behaviors of pre-mixed Fe–2Ni–2Cu–1Mo–1C powders were studied. Results show that green density and spring back effect of pre-mixed powders all gradually increased as the compacting pressure rose. The green density of pre-mixed powder increased with the rise of compacting temperature and then slightly fell, the maximal green density was obtained at 120–140 °C. The degree of effect of warm compaction conditions on green density in turn from big to small followed as compacting pressure, lubrication, compacting temperature, mixing method and compacting speed. Die wall lubrication in combination with warm compaction effectively increased the compact density of pre-mixed powder. Sintered density of pre-mixed Fe–2Ni–2Cu–1Mo–1C material first increased and then fell as the temperatures went up after compacts were sintered at different temperatures for 50 min, but the trends of sintering dilatation were quite the reverse. Sintered density first reduced and then increased with the going on of sintering time at 1300 °C, but the trends of dimension change after sintering were just the reverse.     

Research and Simulation of Influence of Three-Axial Compaction on Powder Metallurgic Products Properties

The warm powder compaction process is simulated by the finite element analysis software, MSCJMARC. The thermal mechanically coupled analysis method is applied on the basis of the updated Lagrangian Method, to simulate the warm powder compaction process. The warm powder compaction process is simulated, and the influence of friction condition and pressing styles are researched on the density of powder green and the mechanics behavior at certain temperature. The results indicate that for cylindrical compacts, with the improvement of the friction condition, the uniformity of distribution of green relative density is largely improved, the pressing force and stress decrease, and the nonconforming pressing processes influence the distribution of green density to some degree. The status of stress distribution of the process that punches firstly press and die finally press is different from the other three processes, and presents the figure of ＇flume ＇.     

Dynamic Compaction of Pure Copper Powder Using Pulsed Magnetic Force

The compaction of pure Cu powder was carried out through a series of experiments using dynamic magnetic pulse compaction, and the effects of process parameters, such as discharge energy and compacting direction, on the homogeneity and the compaction density of compacted specimens were presented and discussed. The results indicated that the compaction density of specimens increased with the augment of discharge voltage and time. During unidirectional compaction, there was a density gradient along the loading direction in the compacted specimen, and the minimum compaction density was localized to the center of the bottom of the specimen. The larger the aspect ratio of a powder body, the higher the compaction density of the compacted specimen. And high conductivity drivers were beneficial to the increase of the compaction density. The iterative and the double direction compaction were efficient means to manufacture the homogeneous and high-density powder parts.