体积分数和烧结温度对(AlSiTiCrNiCu)p/6061Al复合材料的热导率的影响

高熵合金具有高硬度、高强度、耐磨、耐腐蚀、高温热稳定等优异性能,源于金属-金属间天然的界面结合特性,高熵合金与铝合金有良好的界面润湿性。本文采用AlSiTiCrNiCu高熵合金颗粒作为增强相增强铝合金,研究高熵合金体积分数与烧结温度对复合材料导热性能的影响。结果表明,(AlSiTiCrNiCu)p/6061Al复合材料的导热率随着AlSiTiCrNiCu颗粒体积分数的增大而降低,20 vol.% (AlSiTiCrNiCu)p/6061Al复合材料的导热率为61.59 W/(m?K),相比于基体6061Al合金降低了52 %。当体积分数为10%时,随着烧结温度的升高,复合材料的导热率降低,烧结温度为540℃时,复合材料的导热率为65.80 W/(m?K)。TEM分析,高熵合金与铝合金的界面为扩散性界面,没有发生界面发应,有助于导热率的降低。     

高熵合金增强铸造铝合金的组织与性能

采用机械合金化工艺制备了Al_(0.25)Cu_(0.75)FeCoNi高熵合金(HEA)颗粒,并采用挤压铸造工艺制备了高熵合金颗粒增强铝基复合材料(HEA/Al),研究高熵合金颗粒体积分数对复合材料显微组织及力学性能的影响。结果表明,当高熵合金颗粒体积分数为5%时,高熵合金颗粒在基体中分布均匀;随着高熵合金颗粒体积分数增加,复合材料局部出现了团聚的现象,且其硬度逐渐增大,但其抗拉强度和伸长率随着体积分数的增大而减小,其中,当高熵合金颗粒体积分数为5%时,综合性能最佳,抗拉强度相比于基体合金提高了12.5%。     

增强相体积分数和烧结温度对(AlSiTiCrNiCu)p/6061Al复合材料热导率的影响

采用AlSiTiCrNiCu高熵合金颗粒作为增强相增强铝合金,研究高熵合金体积分数与烧结温度对复合材料导热性能的影响。结果表明,(AlSiTiCrNiCu)p/6061Al复合材料的热导率随着AlSiTiCrNiCu颗粒体积分数的增大而降低,颗粒体积分数为20%的(AlSiTiCrNiCu)p/6061Al复合材料的热导率为61.6 W/m·K,相比于基体6061Al合金降低了52%。当增强相体积分数为10%时,随着烧结温度的升高,复合材料的热导率降低,烧结温度为540℃时,复合材料的热导率为65.8 W/m·K。     

等离子烧结AlCoCrFeNiTi_(0.5)/Al复合材料的组织和性能

采用放电等离子烧结制备了AlCoCrFeNiT_i(0.5)高熵合金颗粒含量(体积分数)分别为10%、20%、30%的AlCoCrFeNiTi_(0.5)/Al复合材料。研究了AlCoCrFeNiTi_(0.5)颗粒含量对铝基复合材料力学性能以及微观组织的影响。结果表明,增强体含量低于20%可以同时提高复合材料的室温强度和塑性。当增强体含量为20%时,相比于未增强的试样,抗拉强度和伸长率分别提高90.1%和52%,抗压强度提高76.2%,并仍保持塑性压缩特征。复合材料强度和塑性的提高是由于增强体和基体之间形成了稳定的界面。当增强体含量为30%时,复合材料塑性显著下降,这是由于过多的界面相导致基体损伤。     

体积分数和烧结温度对(AlSiTiCrNiCu)_p/6061Al热膨胀性能的影响

采用AlSiTiCrNiCu高熵合金颗粒(HEA_p)作为增强相增强铝合金,研究高熵合金颗粒体积分数和烧结温度对HEA_p/6061Al复合材料热膨胀系数(CTE)的影响。结果表明:25～100℃时,6061Al合金和AlSiTiCrNiCu高熵合金(HEA)的热膨胀系数分别为23.04×10~(-6)/℃和9.85×10~(-6)/℃;随着高熵合金颗粒体积分数的增高,HEA_p/6061Al复合材料的热膨胀系数明显降低。当保持高熵合金颗粒体积分数不变时,随着温度的升高,HEA_p/6061Al复合材料的热膨胀系数呈现出先增大后保持不变的规律。     

增强体形貌对高熵合金增强铸铝合金组织及性能的影响

本文采用机械合金化工艺制备了两种不同形貌特征的高熵合金（Al0.25Cu0.75FeCoNi）颗粒,一种为椭球状颗粒（平均粒径为53μm,无过程控制剂）;另一种为片状颗粒（平均粒径15μm,有过程控制剂）。采用挤压铸造工艺制备了低体积分数（颗粒含量为5 vol.%）的高熵合金颗粒增强铸造铝合金材料,重点分析了不同增强相形貌对复合材料的组织和力学性能的影响规律。结果表明：在复合材料预制块制备过程中,椭球状高熵合金粉体与铝粉容易混合均匀,而片状高熵合金粉体之间易发生团聚。椭球状颗粒与片状颗粒增强的复合材料的抗拉强度分别达到162MPa和174MPa,比铸铝合金实验基体分别提升了12.5%和 20.8%,但伸长率较铸铝合金基体却发生了明显下降。断口分析表明,椭球状颗粒增强复合材料的断裂以基体的撕裂为主;而片状颗粒增强复合材料则以团聚颗粒的破裂为主。     

SiC颗粒增强铝基复合材料的显微组织与力学性能

采用压铸浸渗法制备了体积分数为50%的SiC/Al-5.3Cu-0.8Mg-0.6Ag-0.5Mn耐热铝基复合材料.通过拉伸测试与组织观察,研究了高体积分数SiC颗粒增强对基体合金的显微组织与力学性能影响.结果表明,在基体Al-5.3Cu-0.8Mg-0.6Ag-0.5Mn合金中掺入高体积分数的SiC颗粒后,复合材料的时效硬化与拉伸性能得到了大幅度的提高,185 ℃峰时效处理后的抗拉强度从356 MPa增大到520 MPa.SiC/Al-5.3Cu-0.8Mg-0.6Ag-0.5Mn复合材料的组织致密,分布均匀,其断裂方式包括界面脱开、基体韧断和增强体开裂.高体积分数SiC颗粒的增强并不改变基体合金的时效析出过程,析出相由Ω相和少量θ＇相组成,但SiC颗粒与基体之间发生了界面反应,生成了纳米级的Al4C3化合物.     

搅拌铸造竹叶灰铝基复合材料的显微组织和力学性能（英文）

以从农业废物中分离出的竹叶灰(BLA)为增强剂,当竹叶灰(BLA)含量分别为2%、4%和6%时,以Al-4.5%Cu合金为基体,采用搅拌铸造方法制备复合材料。该复合材料由于基体和增强粒子之间的有效结合,而具有优越的性能。采用各种试验确定该复合材料的力学性能,如密度、孔隙度、硬度和抗拉强度。将所得结果与基体合金相进行比较。采用OM、SEM-EDAX和XRD分析方法对所选基体合金中增强粒子的分散性进行分析。结果表明,复合材料中BLA颗粒均匀分布于晶体内。此外,还观察到BLA颗粒与基体合金有良好的结合,且界面清晰。随着BLA颗粒质量分数的增加,复合材料的密度降低,而孔隙度增大。当复合材料中BLA颗粒含量达到4%时,材料的硬度和抗拉强度都增加,而当BLA含量进一步增加时,硬度和抗拉强度都会降低。     

Co CrFeNi/6061Al复合材料冷喷摩擦复合增材制造及增强相影响规律研究

采用CoCrFeNi高熵合金颗粒代替传统陶瓷颗粒作为增强相,通过冷喷摩擦复合增材制造技术制备了CoCrFeNi/6061Al复合材料。采用SEM、EBSD、TEM和XRD检测技术对复合材料增材体的微观组织进行了表征,研究了不同CoCrFeNi颗粒体积分数对复合材料增材体微观组织和力学性能的影响。结果表明,冷喷摩擦复合增材制造消除了冷喷涂产生的大量微孔和微裂纹缺陷,实现了均匀致密CoCrFeNi/6061Al复合材料的增材制造。CoCrFeNi颗粒的加入使复合材料增材体晶粒显著细化。CoCrFeNi颗粒与Al基体发生界面反应生成的部分金属间化合物被机械破碎为纳米颗粒分散至Al基体内部。随着CoCrFeNi颗粒体积分数的增加,复合材料增材体的极限抗拉强度和平均显微硬度显著增加。     

原位纳米ZrB2颗粒增强7085铝合金的微观组织与力学性能研究

本文通过原位合成技术，成功制备了纳米ZrB₂颗粒增强7085铝合金基复合材料。采用金相显微镜、扫描电子显微镜、透射电子显微镜、X射线衍射仪进行表征，并进行力学性能测试，研究了ZrB₂纳米增强体对7085铝合金的显微组织和力学性能的影响。结果表明，ZrB₂纳米增强体可以显著提高7085铝合金的强度。但是随着增强体体积分数增大，ZrB₂颗粒团聚现象加剧，不利于复合材料的塑韧性提高。同时，在复合材料中引入微量稀土元素Sc可使纳米ZrB₂颗粒团聚现象得到改善，并进一步细化基体晶粒，使复合材料的强度和延长率都得到提高。当ZrB₂含量为2%(体积分数)、Sc含量为0.4%(质量分数)时，复合材料的抗拉强度为534 MPa、伸长率为10.2%，相较于7085铝合金基体分别提高了17.4%、14.6%。     

ZrO2对钼铼合金微观组织与性能的影响

钼铼合金具有优良的力学性能和机加工性能,是电子、核工业等领域关键的结构材料。在钼铼合金中加入氧化锆,形成弥散强化作用,并结合形变强化来提高材料的力学性能。研究发现,合金粉粒度随着ZrO₂含量的增加而减小,在含量为0.7%时晶粒尺寸最细小均匀;ZrO₂颗粒在合金的变形和断裂过程中表现出钉扎效应,显著提升合金的抗拉强度、屈服强度和断后延伸率等力学性能;ZrO₂强化钼铼合金的抗拉强度和断后延伸率在ZrO₂含量为0.7%时达到最高值,随后减少;ZrO₂基本弥散分布在晶界处并与钼基体形成良好结合界面,可以抑制晶界的迁移,提高钼合金的变形抗力。     

Mechanical Properties of Squeeze-Cast A356 Composites Reinforced With B4C Particulates

In this study, different volume fractions of B₄C particles were incorporated into the aluminum alloy by a mechanical stirrer, and squeeze-cast A356 matrix composites reinforced with B₄C particles were fabricated. Microstructural characterization revealed that the B₄C particles were distributed among the dendrite branches, leaving the dendrite branches as particle-free regions in the material. It also showed that the grain size of aluminum composite is smaller than that of monolithic aluminum. X-ray diffraction studies also confirmed the existence of boron carbide and some other reaction products such as AlB₂ and Al₃BC in the composite samples. It was observed that the amount of porosity increases with increasing volume fraction of composites. The porosity level increased, since the contact surface area was increased. Tensile behavior and the hardness values of the unreinforced alloy and composites were evaluated. The strain-hardening behavior and elongation to fracture of the composite materials appeared very different from those of the unreinforced Al alloy. It was noted that the elastic constant, strain-hardening and the ultimate tensile strength (UTS) of the MMCs are higher than those of the unreinforced Al alloy and increase with increasing B₄C content. The elongation to fracture of the composite materials was found very low, and no necking phenomenon was observed before fracture. The tensile fracture surface of the composite samples was indicative of particle cracking, interface debonding, and deformation constraint in the matrix and revealed the brittle mode of fracture.     

Production of High-Strength Al/Al2O3/WC Composite by Accumulative Roll Bonding

In this study, Al/Al₂O₃/WC composites were fabricated via the accumulative roll bonding (ARB) process. Furthermore, the microstructure evolution, mechanical properties, and deformation texture of the composite samples were reported. The results illustrated that when the number of cycles was increased, the distribution of particles in the aluminum matrix improved, and the particles became finer. The microstructure of the fabricated composites after eight cycles of the ARB process showed an excellent distribution of reinforcement particles in the aluminum matrix. Elongated ultrafine grains were formed in the ARB-processed specimens of the Al/Al₂O₃/WC composite. It was observed that as the strain increased with the number of cycles, the tensile strength, microhardness, and elongation of produced composites increased as well. The results indicated that after ARB process, the overall texture intensity increases and a different-strong texture develops. The main textural component is the Rotated Cube component.     

YbB6 对Ti-6Al-4V钛合金组织和性能的影响

采用放电等离子烧结（SPS）制备了含YbB₆的Ti-6Al-4V钛合金,并研究了YbB₆对Ti-6Al-4V钛合金显微组织和力学性能的影响。结果表明,随着YbB₆含量的增加,复合材料的显微组织发生转变,晶粒明显细化,原位反应生成的TiB晶须和Yb₂O₃颗粒有利于复合材料力学性能的提高。此外,当添加0.6%（质量分数）YbB₆后,烧结样品的相对密度、显微硬度、屈服强度、极限拉伸强度和延伸率分别为99.43%、4030 MPa、903 MPa、1148 MPa和3.3%。与Ti-6Al-4V试样相比,其数值分别提高了0.37%、13.8%、38.07%和17.14%。强化机制主要是组织转变、晶粒细化和弥散强化。随着YbB₆含量的增加,断裂方式主要为韧性断裂和脆性断裂。     

搅拌摩擦加工制备纳米RE/Al2O3增强铝基复合材料

铝基复合材料因其优异的物理性能及机械性能已得到广泛应用.文中通过在2219-O铝合金内部添加不同比例的RE/Al₂O₃纳米粉末,利用搅拌摩擦加工技术,制备铝基复合材料.并对搅拌区进行金相、拉伸、硬度、SEM,EDS和XRD等试验.结果表明,搅拌区金属在搅拌头强烈的搅拌摩擦作用下发生显著的塑性变形和连续动态再结晶,形成细小的等轴晶粒,并具有明显的洋葱环组织.复合材料的抗拉强度为母材的163%、屈服强度为母材的195%,同时硬度也明显增加.但是不同稀土比例对金属基复合材料的组织形貌和力学性能影响不大.大块复合材料制备过程粉末添加及隧道型缺陷的控制是关键.     

体育器材用TiAl3/AlSi11Cu3铝合金组织和力学性能优化

利用超声振动法制备体育器材用AlSi11Cu3铝合金,通过添加K₂TiF₆粉末原位反应生成TiAl₃增强相的方法对铝合金进行颗粒增强,研究了超声功率和颗粒增强对AlSi11Cu3铝合金微观组织和力学性能的影响。试验结果表明,最佳的超声功率为1 kW,超声振动和TiAl₃增强相的引入能明显细化铝合金组织,大幅提升铝合金的拉伸性能和硬度,抗拉强度、伸长率和硬度分别提升了33.9%、23.6%和38.8%,断裂特征由准解理断裂逐渐向韧性断裂转变。     

Fabrication characteristics and tensile strength of novel Al2024/SiC/red mud composites processed via stir casting route

The stir casting technique was used to fabricate aluminum 2024 matrix hybrid composites reinforced with SiC (5%, mass fraction) and red mud (5%–20%, mass fraction) particles. The developed composites were characterized by using scanning electron microscopy (SEM) and electron dispersive spectrum (EDS) techniques. Further, Taguchi's approach of experimental design was used to examine the tensile strength of the hybrid composites (with minimum number of experiments). It was found that the reinforcing particles were well dispersed and adequately bonded in the hybrid composites. The density and porosity of the hybrid composites were reduced with the increase in reinforcement content. The tensile strength of the composites increased with the increase in the red mud content and the ageing time. The developed model indicated that the red mud content had the highest influence on the tensile strength response followed by the ageing time. Overall, it was found that Al2024/SiC/red mud composites exhibited superior tensile strength (about 34% higher) in comparison to the Al2024 alloy under optimized conditions.     

Enhancing strength and ductility of magnesium by integrating it with aluminum nanoparticles

Nano-size aluminum powder (Al_p) reinforced magnesium composites were successfully synthesized using a powder metallurgy technique. Microstructural characterization of the materials revealed fairly uniform distribution of reinforcement. Mechanical properties characterization revealed that the presence of aluminum nanoparticles ⩽1 vol.% leads to an increase in hardness, 0.2% yield strength and ultimate tensile strength of magnesium. The average ductility of the composites was higher when compared with pure magnesium ⩽0.75 vol.% and decreased thereafter. An attempt was made in the present study to correlate the presence of nano-size aluminum reinforcement particles and their increasing number with the microstructural, physical and mechanical properties of magnesium.     

Processing,characterization, room temperature mechanical properties and fracture behavior of hot extruded multi-scale B4C reinforced 5083 aluminum alloy based composites

Microstructural characteristics and mechanical behavior of hot extruded Al5083/B₄C nanocomposites were studied. Al5083 and Al5083/B₄C powders were milled for 50 h under argon atmosphere in attrition mill with rotational speed of 400 r/min. For increasing the elongation, milled powders were mixed with 30% and 50% unmilled aluminum powder (mass fraction) with mean particle size of >100 μm and <100 μm and then consolidated by hot pressing and hot extrusion with 9:1 extrusion ratio. Hot extruded samples were studied by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), tensile and hardness tests. The results showed that mechanical milling process and presence of B₄C particles increase the yield strength of Al5083 alloy from 130 to 566 MPa but strongly decrease elongation (from 11.3% to 0.49%). Adding <100 μm unmilled particles enhanced the ductility and reduced tensile strength and hardness, but using the >100 μm unmilled particles reduced the tensile strength and ductility at the same time. By increasing the content of unmilled particles failure mechanism changed from brittle to ductile.     

Investigation on mechanical properties of aluminium 7075-boron carbide-coconut shell fly ash reinforced hybrid metal matrix composites

The present research work reports the fabrication and evaluation of the mechanical properties of hybrid aluminium matrix composites(HAMC). Aluminium 7075(Al7075) alloy was reinforced with particles of boron carbide(B_4 C) and coconut shell fly ash(CSFA). Al7075 matrix composites were fabricated by stir casting method. The samples of Al7075 HAMC were fabricated with different weight percentages of(0, 3, 6, 9 and 12 wt.%) B_4 C and 3 wt.% of CSFA. The mechanical properties discussed in this work are hardness, tensile strength, and impact strength. Hardness of the composites increased 33% by reinforcements of 12 wt.% B_4 C and 3 wt.% CSFA in aluminium 7075 alloy. The tensile strength of the composites increased 66% by the addition of 9 wt.% B_4 C and 3 wt.% CSFA in aluminium 7075 alloy. Further addition of reinforcements decreased the tensile strength of the composites. Elongation of the composites decreased while increasing B_4 C and CSFA reinforcements in the matrix. The impact energy of the composites increased up to 2.3 J with 9 wt.% B_4 C and 3 wt.% CSFA addition in aluminium alloy. Further addition of reinforcement decreased the impact strength of the composites. The optical micrographs disclosed the homogeneous distribution of reinforcement particles(B_4 C and CSFA) in Al7075 matrix. The homogeneously distributed B_4 C and CSFA particles added as reinforcement in the Al7075 alloy contributed to the improvement of hardness, tensile strength, and impact strength of the composites.