【作者】 陈浩；

【导师】 王志； 许晓静；

【作者基本信息】 江苏大学 ， 机械工程， 2021， 硕士

【摘要】 以铝合金为基体的复合材料具备出色的力学性能,并且已经大范围的应用于航空航天、先进武器、交通运输等重大领域,其中铝合金的系列较多如2000系、5000系、6000系、7000系等等。同时分别以碳化硅晶须(SiC_w)、碳化硅颗粒(SiC_p)增强的铝基复合材料在国内外航空航天、军事领域得到了大规模的应用,充分展现了其独特的性能优势,及其在材料领域的竞争力。本文对以SiC_w与纳米SiC_p混杂增强5083Al铝基复合材料进行深入探究。其中以5083Al合金粉末作为基体,通过粉末冶金(PM)进行复合材料的制备以及对复合材料进行的塑性变形加工,并对其组织性能进行相关分析。本文的研究内容与结果总结为以下四点:(1)研究了20vol%SiC_w与2.4vol%nano-SiC_p混杂增强的5083Al基复合材料的烧结工艺。通过冷压成型后氩气保护烧结来制备烧结态材料,发现当烧结温度为700℃,此时硬度与致密度都达到了峰值,并且在此温度下烧结8h,对于25vol%SiC_w、30vol%SiC_w与2.4vol%nano-SiC_p混杂增强的复合材料同样可以充分烧结。(2)研究了热挤压以及热挤压参数对SiC_w与纳米SiC_p混杂增强的5083Al基复合材料的组织性能的影响。研究表明,热挤压后复合材料的硬度与致密度分别为184HV,97.638%,相比于烧结态样品,硬度与致密度分别提高了约31.1%,11.8%;结果显示挤压比为10:1的硬度与致密度分别为167HV,97.638%,抗压强度与断裂应变分别为705MPa,24.475%;而挤压比为4:1的样品硬度与致密度分别为162HV,95.420%,抗压强度与断裂应变分别为635MPa,17.9%。对比可知,发现在挤压比10:1模具下热挤压的硬度、致密度、抗压强度与断裂应变分别提高了3.1%、2.3%、11%和37%。(3)研究了挤压材-退火对20vol%SiC_w与2.4vol%纳米SiC_p混杂增强的5083Al基复合材料的组织性能的影响,挤压材经300℃、400℃、500℃,3h,6h退火后,其抗拉强度的变化主要取决于退火的时间,而断后伸长率大小主要取决于退火温度。总体上,随着退火温度的升高,退火时间的延长,其塑性越来越好。在500℃×6h退火工艺下,与未退火态相比较,其抗拉强度变化不明显,而断后伸长率提高175%。(4)研究了20vol%SiC_w,25vol%SiC_w,30vol%SiC_w与2.4vol%nano-SiC_p混杂增强的三种5083铝基复合材料组织性能,当SiC_w的含量达到25vol%以上时,材料的强度与塑性发生急剧降低;同时还研究了20vol%SiC_w三模态制备与非三模态制备的复合材料组织性能,结果表明两者区别在于三模态组织的制备能够有效调控复合材料的塑性,其中三模态组织复合材料的断后伸长率与断裂应变分别比非三模态组织的复合材料提高了约18.2%,9.4%。本文将SiC_w与纳米SiC_p进行混杂增强铝基复合材料的组织性能,以高镁合金(5083Al)为基体,通过球磨复合粉末-压制成型-氩气保护烧结-热挤压-退火处理的工艺路线,制备5083Al基复合材料,实现了对粉末冶金工艺中各流程参数与性能间的有效调控。更多还原

【Abstract】 Composite materials based on aluminum alloy have excellent comprehensive properties,and have been widely used in aerospace,advanced weapons,transportation and other major fields,among which there are many series of aluminum alloys,such as 2000 series,5000 series,6000 series,7000 series and so on.At the same time,the aluminum matrix composites reinforced by silicon carbide whiskers(SiC_w)and silicon carbide particles(SiC_p)have been widely used in aerospace and military fields at home and abroad,which fully embodies its remarkable performance advantages and establishes its competitive situation in the material system.In this paper,the 5000 series aluminum matrix composites controlled by SiC_w and nano-SiC_p are deeply explored.With 5083 Al alloy powder as matrix,the composite material was prepared by powder metallurgy(PM),and the plastic deformation process of the composite material was carried out,and the microstructure and properties of the composites were discussed.The research contents and results of this paper are summarized as follows:(1)The sintering process of 5083 Al matrix composites reinforced by 20vol%SiC_w and2.4vol% nano-SiC_p was studied.The sintered materials were prepared by argon protection sintering after cold pressing.It was found that the hardness and density reached the peak when the sintering temperature was 700℃,and the composites reinforced by 25vol%SiC_w,30vol%SiC_w and 2.4vol% nano-SiC_p could also be fully sintered when sintered at this temperature for 8 hours.(2)The effects of hot extrusion and hot extrusion parameters on 5083 Al matrix composites controlled by SiC_w and nano-SiC_p were studied.Hardness and density of the composite material after hot extrusion are 184 HV and 97.638%,respectively,which are increased by about 31.1% and 11.8% respectively compared with the sintered samples.The results show that the hardness and density of the extrusion ratio of 10: 1 are 167 HV and97.638%,and the compressive strength and fracture strain are 705 MPa and 24.475%,respectively.However,the hardness and density of the samples with extrusion ratio of 5: 1are 162 HV and 95.420%,and the compressive strength and fracture strain are 635 MPa and17.9%,respectively.By comparison,it is found that the hardness,density,compressive strength and fracture strain of hot extrusion die with extrusion ratio of 10: 1 are increased by3.1%,2.3%,11% and 37% respectively.(3)The effects of extrusion-annealing on the microstructure and properties of 5083 Al matrix composites reinforced by 20vol%SiC_w and 2.4vol% nano-SiC_p were studied.after annealing at 300℃,400℃,500℃,3h and 6h,the tensile strength of extrusion mainly depends on the annealing time,while the elongation after fracture mainly depends on the annealing temperature.with the increase of annealing temperature and annealing time,its mechanical properties are getting better and better.After annealing at 500℃×6h,the tensile strength has no obvious change,but the elongation after fracture increases by 175%.(4)The properties of three kinds of 5083 aluminum matrix composites reinforced by20vol%SiC_w,25vol%SiC_w,30vol%SiC_w and 2.4vol%nano-SiC_p were studied.When the content of SiC_w is above 25vol%,the strength and plasticity of the materials decrease sharply.The microstructure and properties of the composites prepared by 20vol%SiC_w and nonmodal were also studied.the results show that the difference between them lies in that the preparation of tri-modal structure can effectively control the plasticity of the composites,and the elongation and fracture strain of the composites with tri-modal structure are increased by about 18.2% and 9.4% respectively compared with those with non-modal structure.In this paper,SiC_w and nano-SiC_p are innovatively mixed to control the microstructure and properties of aluminum matrix composites.With high magnesium alloy(5083Al)as the matrix,5083 Al matrix composites are prepared by the process route of ball milling composite powder-press forming-argon protection sintering-hot extrusion-annealing treatment,which realizes the effective control of various process parameters and properties in powder metallurgy process.更多还原