【摘要】：顆粒增強(qiáng)鋁基復(fù)合材料具有高比強(qiáng)度、高比模量、耐磨性及尺寸穩(wěn)定好等優(yōu)異的性能。然而,由于傳統(tǒng)陶瓷顆粒增強(qiáng)鋁基復(fù)合材料的塑性和韌性較差,這限制了其在結(jié)構(gòu)材料方面的應(yīng)用。如何在提高復(fù)合材料強(qiáng)度的同時(shí)又能獲得良好的塑性和韌性,一直是研究者追求的目標(biāo)。多主元高熵合金是一種全新的合金體系,其獨(dú)特的顯微結(jié)構(gòu)使高熵合金具有高硬度、高強(qiáng)度、耐磨、耐腐蝕、高溫?zé)岱�(wěn)定以及特殊的磁、電等眾多優(yōu)異性能。源于金屬-金屬間天然的界面結(jié)合特性,高熵合金與鋁合金基體間的界面潤濕性與界面相容性好。若能采用高熵合金作為增強(qiáng)相來增強(qiáng)增韌鋁合金,將突破傳統(tǒng)陶瓷增強(qiáng)與增韌的瓶頸,實(shí)現(xiàn)復(fù)合材料強(qiáng)度和塑性的同時(shí)提高。然而,迄今為止對采用高熵合金粉體增強(qiáng)相制備高強(qiáng)韌鋁基復(fù)合材料的文獻(xiàn)報(bào)道甚少。本文主要開展了對高熵合金的制備工藝及其增強(qiáng)的鋁基復(fù)合材料的制備及性能方面的研究。首先,采用機(jī)械合金化工藝制備了四種不同成分的高熵合金粉末顆粒,并研究了其合金化行為、相形成規(guī)律以及過程控制劑對粉末粒度、形貌及相組成的影響。結(jié)果表明,四種不同成分的高熵合金都具有簡單的立方結(jié)構(gòu)。通過對比分析在不同工藝下所制備的Al_(0.25)Cu_(0.75)FeNiCo高熵合金粉體,得出采用適當(dāng)時(shí)間的干磨加濕磨的工藝是最好的,不僅得到的粉體顆粒尺寸均勻、細(xì)小,而且出粉率也比較高。通過EDS分析發(fā)現(xiàn),隨球磨時(shí)間增長,引入的雜質(zhì)就會越多。Al_(0.25)Cu_(0.75)FeNiCo高熵合金的最優(yōu)球磨工藝為:干磨16h,濕磨24 h。在相同的工藝(干磨16 h,濕磨24 h)制備不同成分的高熵合金(Al0.5CuFeNiCoCr、AlCuFeNiCoCr、AlCuFeNi CoCrTi0.5),得到的顆粒形貌和尺寸差別都不是很大。分析認(rèn)為,機(jī)械合金化工藝才是影響高熵合金顆粒尺寸和形貌的主要因素,與高熵合金自身的特性關(guān)聯(lián)不是很大。其次,采用粉末熱擠壓法制備高熵合金顆粒增強(qiáng)7075鋁基復(fù)合材料,研究其組織特征與力學(xué)性能。結(jié)果表明:復(fù)合材料棒材表面光滑,沒有開裂現(xiàn)象;復(fù)合材料顆粒分布較均勻,但是增強(qiáng)相顆粒存在少部分開裂、破碎的現(xiàn)象;EDS分析發(fā)現(xiàn)復(fù)合材料中Al_(0.25)Cu_(0.75)FeNiCo高熵合金顆粒擠壓前后其成分保持一致,與基體合金之間沒有出現(xiàn)大規(guī)模的元素?cái)U(kuò)散現(xiàn)象;復(fù)合材料的彈性模量、抗拉強(qiáng)度都優(yōu)于基體合金。再次,對不同體積分?jǐn)?shù)下Al_(0.25)Cu_(0.75)FeNiCo高熵合金顆粒增強(qiáng)鋁基復(fù)合材料研究發(fā)現(xiàn),隨高熵合金顆粒含量的增大,復(fù)合材料中顆粒團(tuán)聚區(qū)域增多,且由團(tuán)聚導(dǎo)致的孔隙數(shù)量增多,尺寸增大,導(dǎo)致致密度降低。隨體積分?jǐn)?shù)的增加,復(fù)合材料的彈性模量和硬度都增大,但復(fù)合材料的抗拉強(qiáng)度和斷后伸長率出現(xiàn)先增大后減小的趨勢。隨著顆粒體積分?jǐn)?shù)的變化,復(fù)合材料的斷口形貌特征無顯著變化,說明體積分?jǐn)?shù)對復(fù)合材料斷裂類型的影響不大。擠壓溫度為400℃,擠壓比λ=17.36,Al_(0.25)Cu_(0.75)FeNiCo體積分?jǐn)?shù)為5%時(shí),復(fù)合材料彈性模量、抗拉強(qiáng)度、以及斷后伸長率分別為79.9 GPa、437.6 MPa和11.42%,高于基體的71.2 GPa、364.5 MPa和8.36%。最后,對不同類型高熵合金顆粒增強(qiáng)鋁基復(fù)合材料對比分析。研究發(fā)現(xiàn):在組織特征上,與(Al_(0.25)Cu_(0.75)FeNiCo)p/7075復(fù)合材料呈現(xiàn)出相似的規(guī)律性,都是隨體積分?jǐn)?shù)的增大,顆粒的團(tuán)聚和破裂現(xiàn)象越嚴(yán)重,隨之帶來孔隙數(shù)量增多,致密度降低;在相同工藝條件下制備的復(fù)合材料中,(Al_(0.25)Cu_(0.75)FeNiCo)p/7075復(fù)合材料在彈性模量、抗拉強(qiáng)度、斷后伸長率都是最好的,但在硬度方面,不同類型高熵合金顆粒增強(qiáng)鋁基復(fù)合材料差別不大;在斷口形貌上,隨著高熵合金顆粒的強(qiáng)度提高,復(fù)合材料的斷裂形式從顆粒與基體合金剝離到顆粒自身斷裂發(fā)生轉(zhuǎn)變。
[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，

本文編號：2378592