高熵合金增强铝基复合材料的制备及性能研究
发布时间：2018-12-14 12:12
【摘要】：颗粒增强铝基复合材料具有高比强度、高比模量、耐磨性及尺寸稳定好等优异的性能。然而,由于传统陶瓷颗粒增强铝基复合材料的塑性和韧性较差,这限制了其在结构材料方面的应用。如何在提高复合材料强度的同时又能获得良好的塑性和韧性,一直是研究者追求的目标。多主元高熵合金是一种全新的合金体系,其独特的显微结构使高熵合金具有高硬度、高强度、耐磨、耐腐蚀、高温热稳定以及特殊的磁、电等众多优异性能。源于金属-金属间天然的界面结合特性,高熵合金与铝合金基体间的界面润湿性与界面相容性好。若能采用高熵合金作为增强相来增强增韧铝合金,将突破传统陶瓷增强与增韧的瓶颈,实现复合材料强度和塑性的同时提高。然而,迄今为止对采用高熵合金粉体增强相制备高强韧铝基复合材料的文献报道甚少。本文主要开展了对高熵合金的制备工艺及其增强的铝基复合材料的制备及性能方面的研究。首先,采用机械合金化工艺制备了四种不同成分的高熵合金粉末颗粒,并研究了其合金化行为、相形成规律以及过程控制剂对粉末粒度、形貌及相组成的影响。结果表明,四种不同成分的高熵合金都具有简单的立方结构。通过对比分析在不同工艺下所制备的Al_(0.25)Cu_(0.75)FeNiCo高熵合金粉体,得出采用适当时间的干磨加湿磨的工艺是最好的,不仅得到的粉体颗粒尺寸均匀、细小,而且出粉率也比较高。通过EDS分析发现,随球磨时间增长,引入的杂质就会越多。Al_(0.25)Cu_(0.75)FeNiCo高熵合金的最优球磨工艺为:干磨16h,湿磨24 h。在相同的工艺(干磨16 h,湿磨24 h)制备不同成分的高熵合金(Al0.5CuFeNiCoCr、AlCuFeNiCoCr、AlCuFeNi CoCrTi0.5),得到的颗粒形貌和尺寸差别都不是很大。分析认为,机械合金化工艺才是影响高熵合金颗粒尺寸和形貌的主要因素,与高熵合金自身的特性关联不是很大。其次,采用粉末热挤压法制备高熵合金颗粒增强7075铝基复合材料,研究其组织特征与力学性能。结果表明:复合材料棒材表面光滑,没有开裂现象;复合材料颗粒分布较均匀,但是增强相颗粒存在少部分开裂、破碎的现象;EDS分析发现复合材料中Al_(0.25)Cu_(0.75)FeNiCo高熵合金颗粒挤压前后其成分保持一致,与基体合金之间没有出现大规模的元素扩散现象;复合材料的弹性模量、抗拉强度都优于基体合金。再次,对不同体积分数下Al_(0.25)Cu_(0.75)FeNiCo高熵合金颗粒增强铝基复合材料研究发现,随高熵合金颗粒含量的增大,复合材料中颗粒团聚区域增多,且由团聚导致的孔隙数量增多,尺寸增大,导致致密度降低。随体积分数的增加,复合材料的弹性模量和硬度都增大,但复合材料的抗拉强度和断后伸长率出现先增大后减小的趋势。随着颗粒体积分数的变化,复合材料的断口形貌特征无显著变化,说明体积分数对复合材料断裂类型的影响不大。挤压温度为400℃,挤压比λ=17.36,Al_(0.25)Cu_(0.75)FeNiCo体积分数为5%时,复合材料弹性模量、抗拉强度、以及断后伸长率分别为79.9 GPa、437.6 MPa和11.42%,高于基体的71.2 GPa、364.5 MPa和8.36%。最后,对不同类型高熵合金颗粒增强铝基复合材料对比分析。研究发现:在组织特征上,与(Al_(0.25)Cu_(0.75)FeNiCo)p/7075复合材料呈现出相似的规律性,都是随体积分数的增大,颗粒的团聚和破裂现象越严重,随之带来孔隙数量增多,致密度降低;在相同工艺条件下制备的复合材料中,(Al_(0.25)Cu_(0.75)FeNiCo)p/7075复合材料在弹性模量、抗拉强度、断后伸长率都是最好的,但在硬度方面,不同类型高熵合金颗粒增强铝基复合材料差别不大;在断口形貌上,随着高熵合金颗粒的强度提高,复合材料的断裂形式从颗粒与基体合金剥离到颗粒自身断裂发生转变。
[Abstract]:The particle-reinforced aluminum-based composite material has excellent properties such as high specific strength, high specific modulus, abrasion resistance and stable size. However, due to the poor plasticity and toughness of conventional ceramic particle-reinforced aluminum-based composites, this limits its application in structural materials. How to achieve good plasticity and toughness at the same time of improving the strength of the composite material has been the goal of the researchers. The multi-main-element high-entropy alloy is a brand-new alloy system, and its unique microstructure makes the high-entropy alloy possess many excellent properties such as high hardness, high strength, wear resistance, corrosion resistance, high temperature and heat stability, and special magnetic and electrical properties. The interface wettability and interface compatibility of the high-entropy alloy and the aluminum alloy matrix are good, due to the natural interface bonding property between the metal and the metal. if the high-entropy alloy can be used as the reinforcing phase for reinforcing the toughened aluminum alloy, the bottleneck of the traditional ceramic reinforcement and the toughening can be broken, and the strength and the plasticity of the composite material can be improved. However, the literature on the preparation of high-toughness aluminum-based composite materials with high-entropy alloy powder has been reported to date. The preparation and properties of high-entropy alloy and its reinforced aluminum-based composites are studied in this paper. First, four kinds of high-entropy alloy powder particles with different components were prepared by a mechanical alloying process, and its alloying behavior, phase formation law and the effect of process control agent on the particle size, morphology and phase composition of the powder were studied. The results show that the high-entropy alloys with four different compositions have a simple cubic structure. The Al _ (0. 25) Cu _ (0. 75) FeNiCo high-entropy alloy powder prepared in different process was compared and analyzed, and it was concluded that the process of dry-grinding and humidifying with proper time was the best, not only the particle size of the obtained powder was uniform, fine, and the powder discharge rate was also high. By the EDS analysis, the more impurities are introduced with the growth of the ball milling time. The high-entropy alloy (Al0.5CuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNi CoCrTi0.5) with different components was prepared by dry-milling for 16h and wet-milling for 24 h. It is considered that the mechanical alloying process is the main factor that affects the size and morphology of the high-entropy alloy, and the correlation with the characteristics of the high-entropy alloy is not very large. Next, a high-entropy alloy particle reinforced 7075 aluminum-based composite was prepared by powder hot extrusion, and its microstructure and mechanical properties were studied. The results show that the surface of the composite material is smooth and there is no cracking, and the distribution of the composite particles is more uniform, but a small part of the reinforced phase particles is cracked and broken. The EDS analysis shows that the Al _ (0.25) Cu _ (0. 75) FeNiCo high-entropy alloy particles in the composite material are consistent with the composition before and after the extrusion. and the elastic modulus and the tensile strength of the composite material are superior to that of the matrix alloy. The results of the study on the Al _ (0.25) Cu _ (0. 75) FeNiCo high-entropy alloy particle-reinforced aluminum-based composite in different volume fractions have found that, with the increase of the content of the high-entropy alloy particles, the agglomeration area of the particles in the composite is increased, and the number of pores caused by the agglomeration is increased, and the size is increased, resulting in a reduction in the density. With the increase of the volume fraction, the elastic modulus and the hardness of the composite material are increased, but the tensile strength and the elongation at break of the composite material are first increased and then decreased. With the change of the volume fraction of the particles, the fracture morphology of the composite material has no significant change, and the influence of the volume fraction on the fracture type of the composite material is not great. The elastic modulus, tensile strength and elongation of the composites were 77.9 GPa, 43.7 MPa, and 11.42%, respectively, and 71.2 GPa, 364. 5 MPa and 8. 36%, respectively, when the extrusion temperature was 400 鈩，
本文编号：2378592
[Abstract]:The particle-reinforced aluminum-based composite material has excellent properties such as high specific strength, high specific modulus, abrasion resistance and stable size. However, due to the poor plasticity and toughness of conventional ceramic particle-reinforced aluminum-based composites, this limits its application in structural materials. How to achieve good plasticity and toughness at the same time of improving the strength of the composite material has been the goal of the researchers. The multi-main-element high-entropy alloy is a brand-new alloy system, and its unique microstructure makes the high-entropy alloy possess many excellent properties such as high hardness, high strength, wear resistance, corrosion resistance, high temperature and heat stability, and special magnetic and electrical properties. The interface wettability and interface compatibility of the high-entropy alloy and the aluminum alloy matrix are good, due to the natural interface bonding property between the metal and the metal. if the high-entropy alloy can be used as the reinforcing phase for reinforcing the toughened aluminum alloy, the bottleneck of the traditional ceramic reinforcement and the toughening can be broken, and the strength and the plasticity of the composite material can be improved. However, the literature on the preparation of high-toughness aluminum-based composite materials with high-entropy alloy powder has been reported to date. The preparation and properties of high-entropy alloy and its reinforced aluminum-based composites are studied in this paper. First, four kinds of high-entropy alloy powder particles with different components were prepared by a mechanical alloying process, and its alloying behavior, phase formation law and the effect of process control agent on the particle size, morphology and phase composition of the powder were studied. The results show that the high-entropy alloys with four different compositions have a simple cubic structure. The Al _ (0. 25) Cu _ (0. 75) FeNiCo high-entropy alloy powder prepared in different process was compared and analyzed, and it was concluded that the process of dry-grinding and humidifying with proper time was the best, not only the particle size of the obtained powder was uniform, fine, and the powder discharge rate was also high. By the EDS analysis, the more impurities are introduced with the growth of the ball milling time. The high-entropy alloy (Al0.5CuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNiCoCr, AlCuFeNi CoCrTi0.5) with different components was prepared by dry-milling for 16h and wet-milling for 24 h. It is considered that the mechanical alloying process is the main factor that affects the size and morphology of the high-entropy alloy, and the correlation with the characteristics of the high-entropy alloy is not very large. Next, a high-entropy alloy particle reinforced 7075 aluminum-based composite was prepared by powder hot extrusion, and its microstructure and mechanical properties were studied. The results show that the surface of the composite material is smooth and there is no cracking, and the distribution of the composite particles is more uniform, but a small part of the reinforced phase particles is cracked and broken. The EDS analysis shows that the Al _ (0.25) Cu _ (0. 75) FeNiCo high-entropy alloy particles in the composite material are consistent with the composition before and after the extrusion. and the elastic modulus and the tensile strength of the composite material are superior to that of the matrix alloy. The results of the study on the Al _ (0.25) Cu _ (0. 75) FeNiCo high-entropy alloy particle-reinforced aluminum-based composite in different volume fractions have found that, with the increase of the content of the high-entropy alloy particles, the agglomeration area of the particles in the composite is increased, and the number of pores caused by the agglomeration is increased, and the size is increased, resulting in a reduction in the density. With the increase of the volume fraction, the elastic modulus and the hardness of the composite material are increased, but the tensile strength and the elongation at break of the composite material are first increased and then decreased. With the change of the volume fraction of the particles, the fracture morphology of the composite material has no significant change, and the influence of the volume fraction on the fracture type of the composite material is not great. The elastic modulus, tensile strength and elongation of the composites were 77.9 GPa, 43.7 MPa, and 11.42%, respectively, and 71.2 GPa, 364. 5 MPa and 8. 36%, respectively, when the extrusion temperature was 400 鈩，
本文编号：2378592
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