添加铝对AlNp/Cu复合材料组织与热性能的影响

为提高高体积分数AlNp/Cu复合材料的致密度,采用粉末冶金液相烧结工艺制备了含10vol%Al的AlNp/Cu复合材料,与未添加Al的AlNp/Cu复合材料以及AlN颗粒表面镀铜的AlNp/Cu复合材料进行了组织与热性能的比较.X射线衍射与显微组织观察表明,添加的Al在烧结过程中扩散至铜基体形成固溶体,并能有效的提高AlNp/Cu复合材料的致密度,添加10vol%Al的复合材料相对密度与未添加Al的AlNp/Cu复合材料相比提高了3.5%.热膨胀试验表明:50～550℃之间,40% AlNp/Cu复合材料、添加10vol%Al的40%AlNp/Cu复合材料及AlN颗粒表面镀铜的40%AlNp/Cu复合材料的平均热膨胀系数分别为15.7、13.4和13.4,热循环后的残余应变分别为0.51%、0.18%和0.24%.Al的添加及AlN颗粒表面镀铜都能有效地降低AlNp/Cu复合材料的热膨胀系数和热循环后的残余应变.与表面镀铜的AlNp/Cu复合材料相比,Al的添加在一定程度上降低了AlNp/Cu复合材料的热传导性能,但材料的制备成本显著降低.     

Ca对原位自生Mg2Si/ZM5复合材料组织与性能的影响

通过真空感应炉中氩气保护,在ZM5熔体中加入Si获得原位反应自生Mg2Si/ZM5复合材料.采用金相显微镜、环境扫描电镜、拉伸实验等研究了Ca对该材料组织与性能的影响规律.结果表明:Ca的加入改变了Mg2Si/ZM5复合材料中Mg2Si相的形貌,使其从不规则的汉字状变成较细小的多角形,从而改善了材料的力学性能;当加入0.05?(质量分数)时,复合材料的室温力学性能最好,屈服强度提高了10.4%,延伸率提高了52.4%;在200℃高温下,当含Ca0.05%～0.10%(质量分数)时其屈服强度和延伸率最好,分别提高了30.1%和92.3%.     

Influence of titanium nitride addition on the microstructure and mechanical properties of TiC-based cermets

In this paper, the TiC-based cermets with addition of TiN were fabricated by a conventional powder metallurgy process. The titanium nitride (TiN) and titanium carbide (TiC) used as starting powders have been synthesized by the self-propagating high temperature synthesis (SHS) method. This exothermic reaction, easy to process, allows to obtain fine and original powders from low-cost raw materials. Cermets obtained by sintering powders of TiC and Mo₂C with nickel binder phase are investigated. The effect of TiN adding on the microstructure and the mechanical properties of these composites are studied. Microstructures have been observed by scanning electron microscopy (SEM). Room temperature mechanical properties such as Young’s modulus, fracture toughness and microhardness have been measured and related to morphology and chemical composition of the samples. Tribological experiments were also performed and the friction coefficient of a cermet containing titanium nitride was compared with that of other hard materials. The SHS starting powders used present some particularities, as it was shown in a previous study [Matériaux à base de carbures et nitrures, pour coupe et usure, obtenus à partir de poudre SHS, PhD Thesis, INSA Lyon, 2004]. The purpose of this work is to show that results concerning the impact of TiN addition on microstructure and mechanical properties obtained on bulk specimens, from these original starting powders, are similar to the ones obtained on alloys from commercial starting powders.     

Influence of Al-Ti-B addition on the microstructure and mechanical properties of A356 alloys

The mechanical properties (σb,σ0.2,and δ) and fracture behavior of tensile specimens of the refined A356 alloys were investigated as a function of the addition level of Al-Ti-B master alloy under both as-cast and T6 heat-treated conditions. The results show that as the addition level of Al-5Ti-1B master alloy increases from 0.1 wt.% to 5.0 wt.%,the mechanical properties of refined A356 alloys improve steadily and then decrease slightly under both as-cast and T6 heat-treated conditions. Also,they display exc...     

热处理工艺对Ni-P-PTFE复合镀层组织与性能的影响

采用扫描电镜、X射线衍射、差热分析研究了热处理对Ni-P-PTFE(聚四氟乙烯)化学复合镀镀层组织的影响,并研究了镀层的磨损性能.结果表明,经400℃×1 h处理后,PTFE的挥发主要发生在镀层的表层,内部的PTFE含量变化很小;镀态条件下,镀层为非晶态,经400℃×1 h处理晶化后生成Ni相及Ni3P相.Ni-P-PTFE复合镀层的晶化起始温度和峰值温度都高于Ni-P镀层.Ni-P-PTFE复合镀层的激活能为235 kJ/mol,与Ni-P镀层的激活能差别不大.镀层摩擦系数在PTFE加入量为8 mL/L时最小,同时镀层磨损量最小;热处理后,Ni-P-PTFE复合镀层表现出较好的耐磨性和较小的摩擦系数.     

Influence of zirconium addition on the microstructure and magnetic properties of nanocomposite Nd10.1Fe78.2-xCo5ZrxB6.7 permanent magnets

Nanocomposite Nd10.1Fe78.2-xCo5ZrxB6.7 （x= 0, 1.5, 2.5, 2.7, 3, 4） permanent magnets were prepared by melt-spun and annealing. The microstructure and magnetic properties of the permanent magnets were investigated. The resuits reveal that the addition of Zr element significantly reduces the grain size and improves the thermal stability of the amorphous phase. A fme nanocomposite microstructure with an average grain size of about 35 nm can be developed at a wheel speed of 16 m·s^-1 with the content of Zr up to 2.7 at.%. After optimal annealing （710℃ x 4 min）, the magnetic properties of the Ndl0.1Fe75.5Co5Zr2.TB6.7 bonded magnets were achieved as follows： Br= 0.72 T, jHc = 769 kA·m^-1, and （BH）max = 85.0 kJ·m^-3.     

添加稀土对新型高强度铸钢组织和性能的影响

通过组织观察和力学性能分析,研究了稀土合金的加入方法和添加量对熔模铸钢组织和性能的影响。结果表明:钢水脱氧后,采用投入法加入适量的稀土合金,可以改善铸钢的夹杂物数量、形态和其铸态显微组织,从而提高铸钢的力学性能。最佳添加量为每100 kg钢水加入300 g稀土硅合金。     

Cu及热处理工艺对9Ni钢组织及性能的影响

通过实验研究了Cu元素及热处理工艺对9Ni低温钢组织与力学性能的影响。结果表明,添加Cu元素后,材料的低温冲击韧性明显得到提升,而抗拉强度和屈服极限变化不大。调质热处理后,材料的力学性能及低温冲击性能均明显得到改善。通过光学显微镜观察发现,热轧态的9Ni钢微观组织主要为淬火马氏体,经热处理后则主要为回火马氏体;进一步通过扫描电镜观察可以发现,调质热处理后,材料的基体组织为回火马氏体,在基体上分布着白亮色的粒状和板条状的淬火马氏体和回转奥氏体混合物。通过X射线衍射检测发现,添加Cu元素后回转奥氏体的数量增加。Cu对9Ni钢低温韧性的改善主要有以下两方面原因:一是钢中Cu、Ni等元素的富集大大提高了回转奥氏体的稳定性并增加了其含量,二是Cu元素的添加使回转奥氏体在晶内、晶界的分布更加均匀、弥散,从而提高了9Ni钢的低温韧性。     

Influence of WC addition on the microstructure and mechanical properties of NbC–Co cermets

NbC–24.5 wt.% Co cermets with up to 30 wt.% WC were obtained by solid state hot pressing at 1300 °C under a pressure of 45 MPa for 10 min and pressureless liquid phase sintering at 1360 °C for 60 min. The effect of WC addition on the microstructure and mechanical properties of NbC–Co based cermets was investigated. The hot pressed cermets exhibited interconnected and irregular niobium carbide (NbC) or (Nb,W)C grains, whereas the shape of the NbC grains changed from faceted with rounded corners to spherical, as the WC content increased in the pressureless sintered cermets. The undissolved WC increased with increasing WC addition. A clear core/rim structure was observed in the hot pressed cermets with 10–30 wt.% WC additions, whereas this structure was gradually eliminated when pressureless sintering. The hardness remains nearly constant whereas the fracture toughness slightly increases with increasing WC addition. The dissolution of WC in the Co binder and NbC grains, as well as the formation of a solid solution (Nb,W)C phase were supported by thermodynamic calculations.     

Bi对铸造Al-Mg2Si金属基复合材料组织与干摩擦磨损性能的影响（英文）

研究不同Bi含量的添加对Al-15Mg2Si原位金属基复合材料组织与干磨擦磨损性能的影响。结果表明,Bi的适量添加对复合材料中的初生和共晶Mg2Si相具有明显的变质效果。含Bi复合材料的磨损率和摩擦系数都小于无Bi复合材料的。Bi改变了复合材料的磨损机理,1%Bi的添加使其从磨粒磨损、粘着磨损和疲劳磨损转变为微弱磨粒磨损和粘着磨损,4%Bi的添加有效地抑制了摩擦表面初生Mg2Si颗粒裂纹的产生,避免了粘着磨损和疲劳磨损,使复合材料的磨损成为单一的微弱磨粒磨损。含Bi复合材料耐磨性能的改善是Bi对Mg2Si相的变质作用和Bi颗粒自润滑作用的综合结果。     

Zr元素对Al-Mn-Si-Zn系铝合金组织与性能的影响

研究Zr添加对Al-Mn-Si-Zn合金显微组织、力学性能及电化学性能的影响。透射电镜观察表明,Zr合金化可使退火态合金中的析出相更加细小、弥散,但是对模拟钎焊态合金的影响较弱。拉伸实验结果表明,添加Zr能够显著提高退火态合金的力学性能,但是对模拟钎焊态合金影响不大。电化学实验结果则表明,Zr元素的添加可降低退火态合金的抗腐蚀性能,但是对模拟钎焊态合金的影响不大。     

铁对粉末冶金法制备铝基复合材料微观组织和力学性能及磁学性能的影响(英文)

研究铁对粉末冶金法制备铝基复合材料微观组织、力学性能及磁学性能的影响。利用机械混合制备含0,5%,10%和15%Fe(质量分数)的铝基复合材料。Al-Fe混合粉末经压制后在真空炉中600°C烧结1 h。XRD结果表明:在含有5%和10%Fe的试样中只有Fe和Al的衍射峰,而含有15%Fe的试样中则存在Al和Al13Fe4的衍射峰。实验结果表明:随着Fe含量的增加,材料的致密度和导热性变差。复合材料中的Fe可以提高其强度和硬度。材料的强化机制包括基体的晶粒细化,Fe颗粒的均匀分布以及Al13Fe4金属间化合物的形成。含有5%Fe试样的磁化强度为0.3816×10-3A·m2/g,对于含有10%Fe的试样,其磁化强度增加至0.6597×10-3A·m2/g,而对于含有15%Fe试样,其磁化强度降低至0.0702×10-3A·m2/g。这是由于在高铁试样中形成了反磁性的Al13Fe4金属间化合物导致磁化强度降低。     

Influence of rare earth Ce addition on the microstructure,properties and soldering reaction of pure Sn

The influence of trace rare earth (RE) Ce addition on the microstructure, melting point and wettability of pure Sn as well as on the soldering reactions in Sn-xCe/Cu(Ni) solder joints was investigated. In bulk Sn-xCe solders, large β-Sn grains were observed with the Ce addition less than 0.2 wt%; while the β-Sn grain size decreased markedly when the Ce addition was 0.2 wt%, resulting in a refined microstructure. The addition of trace RE Ce had little effect on the melting temperature of the solders. Smaller wetting angles of Sn-xCe solders on both Cu and Ni substrates were measured when the samples were reflowed at a higher temperature. The Sn-0.2Ce solder owned the best wettability on Cu substrate. Scallop-like Cu₆Sn₅ intermetallic compound (IMC) grains formed at the Sn-xCe/Cu interfaces, while a continuous Ni₃Sn₄ IMC layer formed at each Sn-xCe/Ni interface. With the increase of Ce addition, the interfacial IMC grain size and the interfacial IMC layer thickness on both Cu and Ni substrates decreased gradually. The activity of Sn was lowered with the Ce addition, which depressed the growth of the interfacial IMC. In the current study, the Ce addition of 0.2 wt% exhibits the optimized performance.     

Influence of Ca addition on microstructure,mechanical properties and corrosion behavior of Mg-2Zn alloy

The microstructure,mechanical properties and corrosion behaviors of as-cast ternary Mg-2Zn-x Ca(x=0,0.2,0.4,0.8)alloys have been investigated in this study.Results indicate that the microstructure of Mg-Zn-Ca alloys can be significantly refined with increasing Ca concentration.Moreover,the alloys with different contents of Ca exhibit the different phases formation behaviors,i.e.α-Mg+Ca_2Mg_6Zn_3 phases for Mg-2Zn-0.2Ca and Mg-2Zn-0.4Ca alloys,andα-Mg+Ca_2Mg_6Zn_3+Mg_2Ca phases for Mg-2Zn-0.8Ca alloy,respectively.Among all the alloys,the maximum ultimate tensile strength and elongation(161 MPa and 9.1%)can be attained for the Mg-2Zn-0.2Ca alloy.Corrosion tests in Hanks’balanced salt solution indicated that Ca addition is detrimental to corrosion resistance of Mg-2Zn alloy.The relationship between as-cast microstructure and properties for different Ca-containing alloys is also discussed in detail.     

Influence of Ti addition on the microstructure and hardness properties of near-eutectic Al–Si alloys

In this study, the influence of Ti addition on the microstructure and hardness of near-eutectic Al–Si has been investigated. Near-eutectic Al–Si alloys (13.1 wt.% Si) with 0.1, 1, 2, 3, 5, and 10% Ti have been utilized for this purpose. The melting operation was carried out in an electrical furnace, where the charge materials were placed in a graphite crucible. After melting, alloys have been cast in the metal mold at 1100 °C and solidified.     

Y对Al-Zr合金微观组织与性能的影响

采用电导率、显微硬度、扫描电子显微镜（SEM）和透射电子显微镜（TEM）研究Al-0．30Zr与Al-0．30Zr-0．08Y合金的微观组织与性能。铸态Al-Zr-Y合金中微米尺度初生Al3Y相通过共晶反应在晶内和晶界上同时生成。在Al-Zr-Y合金中,Y明显加速了Al3Zr（Ll2）的析出动力学。由于较大体积Al3（Zr,Y）析出相的生成,Al-Zr-Y合金的电导率明显高于Al-Zr合金的。在Al-Zr-Y合金中观察到了高密度的弥散球状Ll2结构Al3（Zr-Y）析出相。Al-0．30Zr-0．08Y合金具有比Al-0．30Zr合金更强的抗再结晶能力。     

Effect of Fe addition on microstructure and mechanical properties of Ti-25V-15Cr-2Al-0.2C alloy

1　INTRODUCTIONTitaniumalloyshavebeenextensivelyappliedtoaerospaceindustriesduetotheirexcellentspecificstrength ,goodcorrosionresistanceandmechanicalproperties .However ,conventionaltitaniumalloysarehighlyreactiveandcanundergosustainedcombustionunderconditionsencounteredingasturbineenginescompressors.Intheearly 1990s ,Pratt&Whit ney[13] intheUSAdevelopedanew βtitaniumalloywithgoodburnresistance ,designatedAlloyC (Ti 35V 15Cr) .Theproductioncostofthisalloyisveryhighbecauseofalargeamou…     

Improving microstructure and mechanical properties of Ti43Al5Nb0.1B alloy by addition of Fe

Alloying additions of 0 at%-1.1 at% Fe were added into Ti43A1Nb0.1B alloys for increasing the roomtemperature strength and ductility,and the microstructure and mechanical properties were systematically studied.The results show that the lattice tetragonality(c/a) of γ phase and the average width of columnar grains of alloys decrease with Fe content increasing.Fe addition brings about the formation of Fe-rich B2 phase both in the dendrites and in interdendritic regions,and its content increases with Fe contents increasing.Furthermore,Fe addition aggravates the Al segregations in the interdendritic regions.The alloy with 0.7 at% Fe exhibits higher combined mechanical properties with the ultimate compression strength and fracture strain of 1958.4 MPa and 29.8%,respectively.The grain refinement strengthening and solid-solution strengthening of Fe are responsible for the improvement in the strength and the strain.However,excessive Fe addition results in the decrease in the strength and strain,which is attributed to the severe A1 segregations in the interdendritic regions that cause the premature fracture during compression.     

添加Cr、V元素对Mo2FeB2基金属陶瓷的组织及性能的影响

以Mo、Fe及FeB粉为原料,利用原位反应真空烧结法制备了Mo2FeB2金属陶瓷,研究了添加不同含量的Cr、V等合金元素对材料组织及性能的影响.利用SEM、EDS、XRD等方法,探讨了合金元素的分布及相组成.结果表明,Cr、V在金属陶瓷硬质相及粘接相中都存在,均能细化Mo2FeB2晶粒,添加10wt%Cr、2wt%Ni、2wt%V时,陶瓷材料具有最佳综合力学性能,此时在硬度较高的条件下获得了最高的抗弯强度.     

添加铈对高压压铸AM50镁合金显微组织和力学性能的影响

研究添加铈对高压压铸AM50镁合金显微组织和力学性能的影响.结果表明:添加铈能使AM50镁合金晶粒细化,并使其室温和高温力学性能得到显著改善.相对于未添加Ce和添加0.5％Ce(质量分数)的AM50镁合金,添加1％Ce(质量分数)的镁合金的晶粒更细,力学性能更优.