SiC含量对SiCw/Cu复合材料组织与力学性能的影响

为了研究SiCw/Cu复合材料的制备工艺、形成机理,进一步研究SiC含量对材料的组织结构、力学性能的影响.采用热压法和热等静压法制备了不同SiCw含量的SiCw/Cu复合材料,并对复合材料的致密度、显微组织和物相组成、维氏硬度、拉伸和压缩性能进行了研究,对拉伸断口进行分析.结果表明:SiCw有效阻碍Cu基体晶粒的长大,随着SiCw含量的增加,热压制备的SiCw/Cu复合材料的致密度、断后伸长率、拉伸屈服强度下降,而气孔率、维氏硬度与压缩屈服强度显著增加,抗拉强度先增加后降低.热压制备得到的1wt%SiCw/Cu复合材料,具有相对最优的综合力学性能:抗拉强度为156.9 MPa,拉伸屈服强度为112.5 MPa.采用热等静压法制备的3wt%SiCw/Cu复合材料,各方面性能都要优于相同组分的热压材料,抗拉强度达到175.6 Mpa,拉伸屈服强度达到123.2 MPa,维氏硬度达到101.8 HV.复合材料的强度是SiCw的增强作用与孔隙的弱化作用共同作用的结果,SiCw/Cu复合材料的断裂行为既表现出一定的韧性特征,又表现出一定的脆性特征.     

镁黄铜的组织与性能研究

采用熔铸、挤压的方法制备出了镁黄铜棒材.利用扫描电镜(SEM)、光学显微镜(OM)、X射线衍射仪(XRD)和差热分析仪(DSC)等手段对镁黄铜的微观组织、物相组成和相转变特征、力学性能、切削性能以及腐蚀性能进行了研究.结果表明:合金物相由α相、β相和Cu2Mg相组成,以α相为主;镁黄铜的抗拉强度为494.39MPa,屈服强度为388 56MPa,伸长率为8.78%,布氏硬度为HV140.7,优于铅黄铜;切削性能达到铅黄铜性能的78.5%.研制的镁黄铜替代铅黄铜具有可行性.     

机械合金化合成(ZrC+TiC)/Cu复合材料的研究

以Zr、Ti、Cu和C元素粉末为原料,用XRD、EPMA、SEM、力学性能检测等方法,研究机械合金化合成的ZrC/C和(ZrC FiC)/Cu复合材料的力学和电学性能.实验结果表明:可以用机械合金化合成TiC、ZrC粉末.力学性能方面,经ZrC弥散的Cu基复合材料抗拉强度为359.45MPa,布氏硬度为146.2,经(ZrC TiC)弥散的复合材料抗拉强度为377.3MPa,布氏硬度为166.5,说明ZrC作为第二相可以明显改善Cu基材料的力学性能,而且(ZrC TiC)两相强化效果更好.由断口形貌分析,复合材料主要发生沿界面脆性断裂.电学性能方面,由于致密度不够高以及其他杂质相的引入,材料的相对电导率(IACS标准)有待提高.     

冷轧变形对Al-Cu-Mg合金的显微组织与力学性能的影响

采用光学显微镜、扫描电子显微镜、EBSD技术、透射电子显微镜和万能拉伸试验机等研究了冷轧变形对热轧态Al-Cu-Mg合金显微组织和性能的影响。显微组织观察结果表明，随着冷轧变形量的增加，合金中未溶的Al₂CuMg[Fe, Mn]相和Al₂Cu[Fe, Mn]相发生了破碎。基体中存在较多的棒状Al₂₀Cu₂Mn₃相，该相附近存在大量缠结位错，对合金产生显著强化效果。在冷轧变形量为19%时，位错密度达到最大值。同时，随着冷轧变形量的增加，S、R、Cube、Goss、Brass织构的含量也增加，〈111〉、〈110〉织构的含量降低。力学性能测试结果表明，随着冷轧变形量的增加，合金强度提高，延伸率仍保持较高水平。当冷轧变形量为11%时，合金轧向综合力学性能最佳，抗拉强度为465.0 MPa,屈服强度为291.6 MPa,延伸率为19.0%。此时，合金横向抗拉强度为469.9 MPa,屈服强度为318.0 MPa,延伸率为16.9%。     

变质细化和热处理对挤压铸造成形A356铝合金构件性能的影响

用Al-10Sr变质剂和Al-5Ti-B细化剂处理A356铝合金熔体,并结合挤压铸造和T6热处理工艺,研究变质细化与热处理对A356铝合金挤压铸造件的组织和性能的影响规律。结果表明,随着Al-10Sr变质剂加入量的增加,共晶Si的形貌由片状和长杆状变为颗粒状和蠕虫状,α-Al的晶粒尺寸先减少后增大。当Al-10Sr的加入量(质量分数)为0.3%时,挤压铸造成形件的最优抗拉强度、屈服强度和延伸率分别为221.3 MPa、104.5 MPa和10.3%。Al-10Sr变质能提高形核率、细化α-Al晶粒尺寸和改变共晶硅形貌,使铸造件的力学性能提高。随着A-5Ti-B的增加,晶粒尺寸先降后增,力学性能先增后降。Al-5Ti-B的加入量为0.6%时,最优抗拉强度、屈服强度和延伸率分别为215.6 MPa、106.6 MPa和9.0%。T6热处理(固溶540℃/4 h+时效190℃/4 h)使屈服强度和抗拉强度显著提高和延伸率降低。经过0.6% 的Al-5Ti-B细化处理,T6处理挤压铸造件的最优的抗拉强度、屈服强度和延伸率分别为297.5 MPa、239.3 MPa和8.0%。共晶硅的球化和细化、成形件成分的均匀化以及Mg₂Si强化相在基体中弥散析出,是热处理后构件力学性能提高的主要原因。     

微量硼对Ti-Fe-Cu-Sn-Nb合金力学性能的影响

基于细晶强化和第二相强化原理,通过在一种近β钛合金中加入微量硼(B)元素,以强化该合金.首先设计不同含硼量的Ti85 Fe6 Cu5 Sn2 Nb2合金,并用真空非自耗电弧炉制备,随后对合金在800℃下进行多道次热轧及最终淬火.通过组织观察、拉伸力学性能测试、断口观察及透射电子显微分析,考察不同硼含量对Ti85 Fe6 Cu5 Sn2 Nb2合金组织及力学性能的影响.结果表明,微量硼元素可以使合金的晶粒细化,强度明显提高,但伴随着塑性下降.添加质量分数为0.15％硼可以使合金具有较好的综合力学性能(σ0.2=1105 MPa,δb=4.5％).随着硼含量的增加,合金的强度升高,最高可达1156 MPa.硼的加入在合金中形成正交结构的TiB相,分布于β钛基体中.变形过程中,TiB断裂、TiB割裂基体及其与基体脱粘,产生裂纹源,导致合金塑性下降.     

多道次热挤压制备Al2O3/AZ31复合材料的微观组织与力学性能

采用多道次热挤压制备Al_2O_3颗粒增强AZ31镁基复合材料,利用OM,SEM,TEM对Al_2O_3/AZ31复合材料进行组织观察,利用维氏硬度仪、电子万能拉伸试验机对Al_2O_3/AZ31复合材料进行力学性能测试。结果表明:经过多道次热挤压后,Al_2O_3颗粒均匀地分散在AZ31镁基体中,Al_2O_3颗粒对基体组织的晶粒细化作用得到增强,复合材料的晶粒尺寸随着道次的增加而显著减小。经过4道次热挤压后,Al_2O_3/AZ31复合材料的力学性能显著提高,其硬度,抗拉强度和屈服强度分别达到89HV,305MPa和198MPa,相比于第1道次热挤压后,其硬度,抗拉强度和屈服强度分别提高了19.2%,14.8%和14.1%。     

固溶时间对半固态挤压成形Al-17Si-4Cu-0.5Mg合金组织及力学性能的影响

采用半固态挤压成形工艺制备过共晶Al-17Si-4Cu-0.5Mg合金,研究固溶时间对过共晶Al-17Si-4Cu-0.5Mg合金组织及性能的影响.结果表明,随着固溶时间的增加,Si相出现球化,固溶时间为10 h时,共晶Si的圆整度为0.72.铸态下Si相周围富集较高浓度的Cu元素,固溶1 h后,Cu元素快速固溶到基体中.固溶时间从1 h增加到16 h,在XRD曲线上的θ(Al2 Cu)和Q(Al5 Si6 Cu2 Mg8)相的衍射峰强降低,合金基体中的位错密度大量减少.经180℃,时效处理12 h后,组织中析出针状的θ'相和短棒状的Q'相.随着固溶时间的增加,合金强度值呈现"双峰"现象.固溶1h后,合金的抗拉强度为269 MPa,屈服强度为233 MPa,与未热处理合金相比,抗拉强度和屈服强度分别提高了43.3％和42.7％,合金强度的提高是由于在固溶初期基体中仍有较大的位错密度,时效处理后析出相对位错有较强的钉扎阻碍作用.固溶时间为10 h时,合金的抗拉强度为311 MPa,屈服强度为263 MPa,达到第二个强度峰值,Si相的圆整化和细小析出相的弥散强化作用是形成第二个强度峰的主要原因.     

TiB2/Al-Cu-Li复合材料时效析出及组织演变对力学性能的影响

研究了TiB₂/Al-Cu-Li复合材料T6工艺的微观组织演变和时效析出对力学性能的影响。通过气氛保护熔炼法制备了TiB₂/Al-Cu-Li复合材料。结果表明：在铸态合金的微观组织中,TiB₂颗粒和共晶相主要分布在晶界周围。均匀化处理后,大部分共晶相回溶。轧制变形后,TiB₂颗粒沿着轧制方向被拉长,产生了大量位错。固溶处理削弱了轧制产生的Brass织构和S织构,回溶了轧制产生的析出相。在175℃温度下进行时效,欠时效过程中,δ’(Al₃Li)/β’(Al₃Zr)为主要析出相。随着时效时间的增加,到22 h峰时效时,T1相为主要析出强化相。通过位错强化和析出强化的共同作用,随时效时间增加,屈服强度和抗拉强度先上升后下降,延伸率持续下降。复合材料峰时效的极限抗拉强度为562.7 MPa,屈服强度为475.9 MPa,延伸率为4.5%。     

石墨烯调控3D打印功能钛的组织和性能

用选区激光熔化(SLM)技术制备多孔石墨烯/钛复合材料，研究了石墨烯(Gr)作为增强相对其微观结构、力学性能以及抗腐蚀性能的影响。结果表明：用SLM制备的多孔钛由较小的等轴晶组成，石墨烯加入使其晶粒尺寸进一步减小，石墨烯没有在Ti基体中团聚，部分石墨烯与Ti原位生成的TiC产生了弥散强化。多孔Gr/Ti复合材料的压缩曲线由弹性变形阶段、应力平台阶段和致密化阶段组成，其硬度、抗压强度和压缩率分别为503HV、317.38 MPa和42%；其抗腐蚀性能高于纯钛，腐蚀电位为-0.325 V，腐蚀电流密度为3.28×10^-7 A·cm^-2。     

Contribution of Ti addition to characteristics of extruded Cu40Zn brass alloy prepared by powder metallurgy

The aim of this paper was to investigate the properties of Cu40ZnTi for the purpose of developing a new high-strength, lead-free brass by powder metallurgy. The effect of Ti addition on precipitation hardening behavior of Cu40Zn (denoted as BS40) brass was studied with respect to mechanical properties and microstructures. BS40 and Cu40Zn − 1.0 wt.%Ti (denoted as BS40-A) brass powders were prepared by water atomization process, and β phase was retained in the raw powders predominately. The BS40 powder and Ti powder were elementally mixed to prepare Cu40Zn + 0.5 wt.%Ti (denoted as BS40-B) and Cu40Zn + 1.0 wt.%Ti (denoted as BS40-C) premixed powders. The alloy powders and premixed powders were solidified at 1053 K for 600 s by spark plasma sintering (SPS) and extruded subsequently. It was observed that Cu₂ZnTi intermetallic compound (IMC) and CuZnTi metastable phase resulted from the reaction between Ti and CuZn showed distinct grain refinement effect on extruded Cu40Zn brass. Thus, the excellent strengthening effect processes by precipitation hardening and deform working was obtained, which responding to an yield strength of 345 MPa, and a ultimate tensile strength of 597 MPa, showed 65.9% and 30.4% higher than that of extruded Cu40Zn brass, respectively.     

Investigation on preparation and mechanical properties of W–Cu–Zn alloy with low W–W contiguity and high ductility

In order to improve the mechanical properties of the W–Cu alloy, the W–Cu–Zn alloys with low W–W contiguity were fabricated by three different preparation methods. For the first method, the mixed powder of copper-coated tungsten powder and Zn powder was sintered by SPS (Spark Plasma Sintering) process. For the second method, the mixed powder was processed by CIP (Cold Isostatic Pressing) before SPS. For the third method, a skeleton of the copper-coated tungsten powder was prepared by CIP, and then the skeleton was infiltrated with H70 brass. The microstructure, mechanical properties and failure mechanism of the prepared W–Cu–Zn alloys were investigated. The results show that the W–Cu–Zn alloy fabricated by the third method achieves a high relative density of 98.4% and a low W–W contiguity of 10%. The alloy exhibits a high dynamic compressive strength of 1000 MPa, with a high critical failure strain of 0.7. The Cu-Zn matrix of the alloy fabricated by the third method is composed of α-phase Cu–Zn alloy and Cu₃Zn particles. The homogeneous distribution of Zn in the matrix manifests good solution strengthening effect and the uniformly distributed Cu₃Zn particles has a strong precipitation strengthening effect, which are both responsible for the evidently enhanced mechanical properties.     

TiC-TiB2/Cu复合材料的自蔓延高温合成研究

采用SHS/PHIP工艺制备了TiC-TiB₂/Cu复合材料,通过实验研究了该系列复合材料的微观结构特征和力学性能。结果表明,TiC-TiB₂/Cu复合材料中只有TiC、TiB₂和Cu相存在;随着Cu含量的增加,燃烧温度下降,材料的颗粒尺寸变小;TiC-TiB₂/Cu复合材料的相对密度、抗弯强度和断裂韧性均随Cu含量的增加呈先增后减趋势,当Cu含量为20％时强度最高为580MPa,Cu含量为40％时韧性最高为8.1MPa·m^1/2。     

Biodegradable Zn–3Cu and Zn–3Cu–0.2Ti alloys with ultrahigh ductility and antibacterial ability for orthopedic applications

Zinc(Zn) and its alloys have been proposed as biodegradable implant materials due to their unique combination of biodegradability, biocompatibility, and biofunctionality. However, the insufficient mechanical properties of pure Zn greatly limit its clinical application. Here, we report on the microstructure, mechanical properties, friction and wear behavior, corrosion and degradation properties, hemocompatibility, and cytocompatibility of Zn–3 Cu and Zn–3 Cu–0.2 Ti alloys under three different conditions of as-cast(AC),hot-rolling(HR), and hot-rolling plus cold-rolling(HR + CR). The HR + CR Zn–3 Cu–0.2 Ti exhibited the best set of comprehensive properties among all the alloy samples, with yield strength of 211.0 MPa, ultimate strength of 271.1 MPa, and elongation of 72.1 %. Immersion tests of the Zn–3 Cu and Zn–3 Cu–0.2 Ti alloys in Hanks’ solution for 3 months indicated that the AC samples showed the lowest degradation rate,followed by the HR samples, and then the HR + CR samples, while the HR + CR Zn–3 Cu exhibited the highest degradation rate of 23.9 m/a. Friction and wear testing of the Zn–3 Cu and Zn–3 Cu–0.2 Ti alloys in Hanks’ solution indicated that the AC samples showed the highest wear resistance, followed by the HR samples, and then the HR + CR samples, while the AC Zn–3 Cu–0.2 Ti showed the highest wear resistance.The diluted extracts of HR + CR Zn–3 Cu and Zn–3 Cu–0.2 Ti at a concentration of ≤25 % exhibited noncytotoxicity. Furthermore, both the HR + CR Zn–3 Cu and Zn–3 Cu–0.2 Ti exhibited effective antibacterial properties against S. aureus.     

Mg-13Gd-1Zn合金的组织与力学性能

研究了铸态、退火态、挤压态和T5时效态Mg-13Gd-1Zn三元合金的显微组织和力学性能。结果表明,合金的铸态组织由α-Mg、(Mg,Zn)₃Gd和14H-LPSO长周期相组成。合金在均匀化退火和热挤压后的直接时效(T5)过程中都发生了晶内14H-LPSO相的沉淀析出,表明合金中14H-LPSO的沉淀相变发生在一个很宽的温度范围(200~510℃)。在挤压后合金的直接时效(T5)过程中发生了β'及β₁相的沉淀析出。在沉淀强化和LPSO强化的共同作用下,合金的屈服强度、抗拉强度和伸长率分别为197 MPa、397 MPa和2.56%。在200℃/80 MPa和200℃/120 MPa两种实验条件下,Mg-13Gd-1Zn合金的抗蠕变性能均优于WE54合金。     

Effect of Cu/Zn on microstructure and mechanical properties of extruded Mg–Sn alloys

In this paper, the effect of Cu and Zn addition on mechanical properties of indirectly extruded Mg–2Sn alloy was investigated. Mg–2Sn–0.5Cu alloy exhibits a moderate yield strength (YS) of 225?MPa and an ultimate strength of 260?MPa, which are much higher than those of the binary Mg–2Sn alloy, and the elongation (EL) evolves as ～15.5%. Mechanical properties of the Mg–2Sn–0.5Cu alloy are deteriorated with more 3 wt-% Zn addition, and YS and EL are reduced as 160?MPa and ～10%. The detailed mechanism is discussed according to the work-hardening rate and strengthening effect related to the grain sizes, second phases and macro-textures. Grain refinement and proper texture are believed to play a critical role in both strength and ductility optimisation.     

原位生成棒晶增强Ti-B-C复相陶瓷的研究

Ｂ_４Ｃ与Ｔｉ在１８００°Ｃ×３５ＭＰa×１ｈ的烧结条件下反应生成了TiB₂ 棒晶,棒晶长度在１０～３０μｍ,其长径比在２～８范围．原位生成的棒晶赋予了材料具有极高的力学性能,材料的弯曲强度和断裂韧性分别为 ６８０ＭＰａ和 １２ＭＰａ·ｍ^１／２．通过 Ｘ射线衍射检测了材料的物相组成,利用扫描电镜及透射电镜观察了材料的显微结构．最后讨论了温度及金属Ｔｉ含量对棒晶ＴiＢ₂的生成及发育的影响．     

陶瓷颗粒增强Cr0.5MoNbWTi难熔高熵合金复合材料的制备及其力学性能

难熔高熵合金因其优异的力学性能、高温稳定性和抗氧化性能等,作为高温结构材料具有广阔的应用前景.为了进一步提升材料的力学性能,本研究利用原位反应烧结制备了陶瓷颗粒增强难熔高熵合金复合材料,并探讨了陶瓷增强相的生成机理及其对复合材料力学性能的影响.通过机械合金化制备了含有碳氮氧非金属元素的Cr0.5MoNbWTi过饱和体心...     

Microstructure,mechanical properties and machinability of Cu–Zn–Mg and Cu–Zn–Sb brass alloys

Lead-free alloys have attracted great attentions recently due to the toxic nature of lead for the human body. In this study, low amounts of Mg and Sb were added to the Cu65–Zn35 brass and microstructure, mechanical properties and machinability of samples were compared to Cu65–Zn35 brass. Both Mg and Sb led to the promotion of β′ phase as well as the formation of new ternary copper rich intermetallic particles. It was found that these particles had a significant role in the reduction of the ultimate tensile strength, toughness, work hardening and elongation while increasing the hardness of samples. Results of machinability evaluation of samples showed that the cutting forces were decreased significantly and morphology of chips were improved compared to Cu65–Zn35 brass sample.     

Cu含量对铝基结合剂及其金刚石工具性能的影响

以Al-Cu-Mg-Ti-Cr混合金属粉末为结合剂,利用热压烧结法制备金刚石工具,研究了Cu含量对铝基结合剂及其工具性能的影响。结果表明:随着Cu含量增加,结合剂烧结体的抗弯强度和相对密度先增大后减小,而硬度呈现逐渐增大的趋势。Cu粉的加入可以促进Al2CuMg强化相和Al3Ti、Al2Cr弥散相的形成,细化烧结体晶粒,阻碍晶粒位错运动,从而提高烧结体的力学性能。当Cu的质量分数为4.5%时,烧结体的综合力学性能最优,抗弯强度和硬度分别为334 MPa和98HRB,相对密度达到98.94%。此时,铝基结合剂对金刚石的包镶能力较好,金刚石工具试样强度损失率达到最低,为12.8%,磨削比提高9.7%,被磨削工件表面粗糙度达到0.092μm。