添加青铜粉对烧结316L不锈钢组织和性能的影响

研究了添加青铜粉对316L烧结不锈钢的密度、硬度和微观组织的影响。结果表明：添加青铜粉末提高了316L不锈钢的生坯密度。烧结样品的密度和硬度均随青铜粉体积分数的增大而提高，烧结温度升高也有利于316L烧结不锈钢密度和硬度的增大，最佳烧结温度为1200℃左右。当青铜粉的体积分数为30％、烧结温度为1200℃时，316不锈钢的最大相对密度和硬度分别为95．1％和HRB83。添加青铜粉引起的液相烧结使不锈钢颗粒球形化趋势明显，颗粒表面平直化。     

Influence of the SiC content and sintering temperature on the microstructure,mechanical properties and friction behaviour of sintered self-lubricating composites

This work reports the development of a new, low-friction coefficient combined with high mechanical strength and scuffing resistance of self-lubricating composite produced by powder injection moulding process and the recently introduced plasma-assisted debinding and sintering process. We present and discuss the effect of sintering temperature and SiC content on the microstructure, mechanical and friction properties. Three different temperatures (1100,1150, 1200°C) and six different SiC contents (0–5%) were analysed. SiC content had a paramount role on the microstructure, mechanical and friction behaviour. Sintering temperature had almost no effect on the friction coefficient. However, the sintering temperature strongly influences scuffing resistance. Raman spectra obtained in the central region of the wear scar indicate the presence of turbostratic two-dimensional graphite. The misorientation between graphene planes and the increase in interlamellae distance may induce a low interaction between these atomic planes and are, probably, the origin of the low-friction coefficient.     

Si和La元素对Mo丝显微组织与力学性能的影响

系统研究了La、Si单元掺杂和复合掺杂对钼丝的显微组织和力学性能的影响及其作用机制,优化出具有优异力学性能的Mo-Si-La合金丝的成分为Mo-0.15Si-(0.5～0.8)La.MoSi2与Mo原位反应生成Mo5Si3和Mo3 Si硬质相,起到良好的晶粒细化作用和弥散强化作用.La2O3颗粒通过延迟微裂纹的形成和扩...     

Effect of copper and molybdenum additions on the microstructure and mechanical properties of steel shot

The effect of copper and molybdenum additions on the microstructure of particles produced by the atomization of an iron-carbon melt by an air-water jet using a new atomizer unit has been studied. The application of air-water atomization instead of water atomization is shown to intensify the solidification of particles with a fine microstructure. The introduction of molybdenum (up to 0.6 wt %) into a melt refines the structural constituents of the granules and decreases the fraction of the retained austenite, and the introduction of copper (up to 0.8 wt %) leads to the opposite results. The addition of copper (up to 0.6 wt %) and molybdenum (up to 0.6 wt %) to a melt results in a homogeneous microstructure consisting of fine acicular martensite and fine molybdenum carbides. Low-temperature vacuum tempering at 350°C for 1 h leads to insignificant decarburization of the martensite and the precipitation hardening of the base metal due to copper alloying. The microstructure of a steel alloyed by molybdenum and copper provides an increase in the wear resistance of the steel shot by a factor of 1.5–2 and high quality of the shot (close to the best foreign analogs).     

Effect of boron on microstructure and mechanical properties of PM sintered and nitrided steels

Abstract

PM Distaloy and Astaloy alloys have many applications in the automotive industry and are used in structural elements with different wear resistance values. Their main features are adequate density, hardness, tensile strength, and good ductility. For the purpose of the experiment presented here, Distaloy SA and Astaloy Mo powders, alloyed with various amounts of elemental boron powder, were used. The Distaloy and Astaloy alloys were produced through mixing, compacting, and sintering at t=1393 and 1473 K, and, after the completed sintering process, they were plasma nitrided at 793 K. Experimental results showed that if boron was added, while sintering, the shrinkage phenomena increased ( 1473 K) and some parameters of those alloys (density, hardness, and tensile strength) were improved. Upon the ion nitriding treatment of the surface of base Astaloy Mo samples, a surface layer was created composed of the ε solution and γ' nitride, whereas the surface layer on the Distaloy SA base was mainly composed of a γ' compound. Boron activates the sintering process of Distaloy SA and Astaloy Mo samples but it has no significant impact on the surface layer's thickness of Distaloy SA alloys as opposed to Astaloy Mo alloys in which boron promotes a greater thickness of surface layers along with a reduced depth of nitrogen diffusion.     

气流磨处理对烧结钨粉微观组织和力学性能的影响

采用气流磨分级技术对商业钨粉进行改性,研究气流磨处理和不同粒度搭配对钨粉粉末烧结体微观组织和力学性能的影响.结果表明,经气流磨分级处理后,粒度分布较窄的钨粉能实现良好的堆积均匀性,消除团聚体在烧结过程中形成的不规则粗孔,提升粉末烧结均匀性,提高烧结后期整体相对密度;烧结相对密度由90.7％提高至92.8％,抗弯强度由2...     

锰源粉末对Fe-Mn-C烧结钢组织和力学性能的影响

以电解锰粉和Fe-76% Mn粉末（质量分数）为原料,在600℃和70% N₂+30% H₂混合气体（体积分数）管式炉中氮化得到三种抗氧化含氮锰源粉末（Mn-3% N、Mn-5% N和FeMn-3% N,质量分数）,研究锰含量以及锰源粉末种类对压制烧结Fe-Mn-C烧结钢组织和力学性能的影响。研究表明:使用氮化锰源粉末制备的Fe-Mn-C烧结钢的力学性能明显优于采用电解锰粉为原料制备的同类材料,随着锰源粉末中N含量的升高,烧结钢烧结膨胀率减小,对合金的强化作用增加。以Mn-5% N作为锰源制备的Fe-2Mn-0.5C烧结钢,其拉伸强度为576 MPa,断后延伸率为3.8%,与电解锰粉为锰源相比,烧结钢的拉伸强度和断后延伸率分别提升了29%和123%。使用氮化锰粉作为锰源的烧结钢内孔隙数量减小,珠光体增多,片层间距降低。     

Effect of the additions of carbide-forming elements on the microstructure and mechanical properties of steel shot

The effect of the additions of carbide-forming elements (vanadium, titanium, chromium, molybdenum) on the microstructure and mechanical properties of the steel shot produced by the atomization of an iron-carbon melt (0.8% C) by water at a low pressure (0.2 MPa) is studied. The introduction of alloying elements is shown to affect the sizes of the structural constituents that form during the solidification of shot particles and, hence, the mechanical properties (hardness, wear resistance) of the shot. The additions can decrease the grain size in the shot by a factor of 2.5–3. The formation of the MC (M is a carbide-forming element), VC, TiC, or M ₂C (e.g., Mo₂C) carbide increases the hardness of the shot material. Chromium and molybdenum form solid solutions with iron and complex (Fe, M)₃C carbides.     

Ca和Sr对铸态Mg-Sn-Si合金组织和性能的影响

用X射线衍射仪(XRD)、扫描电镜(SEM)、光学显微镜(OM)研究了铸态Mg-Sn-Si-Ca-Sr合金的相组成和显微组织,用力学性能试验机测定了合金的拉伸性能.结果表明,Mg-5Sn-xSi-0.5Ca-0.5Sr(x=1,2)合金由α-Mg、Mg2Sn、Mg2Si和CaMgSn相所组成,Mg2Si相含量随Si元素的增加而增加.对于Mg-5Sn-1Si-yCa-0.5Sr(y=0.5,2)合金,Ca的质量分数提高到2%后会促进Mg2Ca相和CaMgSn相形成,但同时抑制了Mg2Sn、Mg2Si相的析出,从而导致合金性能下降.对于Mg-5Sn-2Si-0.5Ca-ySr(y=0.5,2)合金,当Sr的质量分数由0.5%提高到2%时,Mg2Si和Mg2Sn相均得到显著细化,并促进了基体内MgSn(Sr,Ca)相形成,从而提高了合金的抗拉强度与屈服强度.     

Mn含量对粉末冶金铁铜碳低合金钢组织与力学性能的影响

采用铜粉、石墨粉和铁粉为原料,以Fe-74.8Mn-6.9C中间合金粉的形式加入Mn元素,制备粉末冶金Fe-x Mn-(2-x)Cu-0.3C(x=0,0.2,0.4,0.6,0.8,1。质量分数,%)低合金钢,研究Mn含量对该合金组织与力学性能的影响。结果表明,合金组织由铁素体和珠光体构成。加入含Mn中间合金粉对混合原料粉末的压制性能没有明显影响。随Mn含量增加,合金中孔隙的数量增多,尺寸变大;合金密度先升高后降低,Mn含量为0.4%时合金密度最大,达到7.24 g/cm~3;合金硬度先升高后降低,Mn含量为0.6%时硬度最大;合金抗弯强度下降,冲击韧性升高,Mn含量超过0.4%时二者变化均较小。因此Fe-0.6Mn-1.4Cu-0.3C合金具有较好的综合性能,硬度(HRB)和冲击韧性分别达到57.4和8.80 J/cm~2,比Fe-2Cu-0.3C合金分别提高5.3和0.82 J/cm~2,材料呈部分韧性断裂特征。     

Study on microstructure and mechanical properties of spark plasma sintered Alumix 431 powder

Spark plasma sintering (SPS) has been used to successfully densify a 7075 aluminium alloy obtained from Alumix 431 powder. Sintering experiments were conducted at the temperature of 450 and 500°C for 2.5, 5 and 10?min. All the presented results confirm the excellent sinterability of Alumix 431 powder in vacuum during the SPS process and clearly show the effect of sintering temperatures and holding times on the densification, microstructure and mechanical properties of the obtained sintered compacts. The best results of hardness (1412?±?39?MPa), tensile strength (345?±?15?MPa) and compressive strength (618?±?4?MPa) were obtained by the compacts sintered at 500°C for 5 min.     

Effect of copper additions on the mechanical properties of iron

The effect of copper alloying on the mechanical properties of iron is studied. Alloying of a model material (armco-iron) with 0.2–2.0% Cu is shown to increase the strength characteristics by a factor of 1.5–2.5 and to decrease the ductility by 8–60%.     

Effect of process parameters on the microstructure and mechanical properties of vacuum hot-press sintered Co-50 mass% Cr alloys

In the present research, two different compositions of submicron-structured cobalt (800?±?45?nm) and chromium (700?±?50?nm) powders are mixed to fabricate Co-50 mass% Cr alloys by the vacuum hot-press sintering technique. This study imposes various hot-press sintering temperatures (1150, 1200, 1250 and 1300°C) and pressures (20, 30, 40 and 50?MPa) while maintaining the sintering time at 1?h, respectively. The experimental results show that the optimum parameters of hot-press sintered Co-50 mass% Cr alloys are 1200°C at 50?MPa for 1?h. Meanwhile, the sintered density reaches 7.73?g?cm^?3, the closed porosity decreases to 0.31%, and the hardness and transverse rupture strength values increase to 80.6?±?0.3 HRA and 1052.9?±?17.5?MPa, respectively. Grain growth is not obviously generated after 1200°C hot-press sintering at 50?MPa for 1?h. Consequently, the optimal solid-phase sintering process effectively improved hot-press sintered Co-50 mass% Cr alloys, which resulted in the good properties.     

添加Dy2O3的烧结钕铁硼磁体的磁性能与力学性能

应用常规粉末冶金工艺制备添加不同质量分数Dy2O3的32(Pr-Nd) -0.60Gd -0.55Nb -0.20Cu -0.45Al - 1.12B - Fe烧结磁体,分析了磁性能、抗弯强度、显微组织的变化规律.结果表明,添加Dy2O3使磁体内禀矫顽力近似线性地上升,而剩磁与磁能积则近似线性地下降;添加1.0％的Dy...