多孔铝合金的压缩应力-应变特征及能量吸收性能

研究了多孔ZL101铝合金(AlSi7Mg0.45)的压缩应力应变曲线与孔结构的关系. 随孔径的减小, 它的弹性模量从270MPa增加到550MPa; 屈服强度(σc)从3MPa增加到20MPa; 随孔隙率的减小, 屈服强度增加. 多孔铝合金具有高的比强度, 其σ2/3c/ρ(梁)及σ1/2c/ρ(板)分别为2.5～7.0和1.6～4.1, 与钢和Al合金相当, 而密度只有Al合金的40%, 可用作轻质结构材料; 它的吸能能力(C)可达到3～7MJ/m3, 又可用作吸能缓冲材料使用.     

中孔隙率通孔多孔铝合金的压缩性能研究

在采用复模铸造工艺制备孔径3.5~4.0 mm、孔隙率65.8%~87.3%的通孔多孔铝合金基础上,通过单轴压缩试验,研究通孔多孔铝合金的压缩性能和吸能能力。通孔多孔铝合金单轴压缩应力应变曲线,呈现线弹性变形、塑性平台段和压缩紧实阶段3个阶段。通孔泡沫铝合金的压缩屈服强度、吸能能力随孔隙率增大而减小,通孔多孔铝合金的压缩屈服强度与Gibson-Ashby的模型拟合结果吻合。     

HD+SPS多孔镁的制备及其组织性能研究

利用氢化脱氢(HD)+放电等离子烧结(SPS)工艺制备了多孔镁块体材料,研究了不同MgH_2含量下多孔镁孔隙率、孔结构及压缩和吸能性能。结果表明,HD+SPS法制备的总孔隙率分别为7.5%和17.8%的多孔镁,且其孔径尺寸细小,内部组织均匀;孔隙率为17.8%的多孔镁具有相对较低的压缩屈服强度43 MPa,单位体积吸能较高,为34.04 MJ/m~3,最大能量吸收效率为1.42。17.8%孔隙率的多孔镁压缩应力-应变曲线较7.5%孔隙率的多孔镁有相对较低的屈服强度及较长的应力平台阶段,在能量吸收材料应用上更具优势。     

钪锆元素增强泡沫铝合金的压缩和吸能性能

采用熔体发泡法制备孔隙率为71.5%~72.5%、孔结构均匀的泡沫Al-0.2Sc-0.17Zr合金。研究孔结构、胞壁显微组织以及等时时效对其压缩和能量吸收性能的影响。结果表明:泡沫铝合金的孔径约为1 mm,且多呈球形;初生Al3(Zr,Sc,Ti)相具有层状结构,并能有效细化铸态晶粒(尺寸约为50μm);在200~600℃等时时效过程中,泡沫试样的压缩性能随温度升高呈现先升高后下降的趋势,325和425℃分别表现出由Sc和Zr大量析出引起的两个明显的强度峰;时效至425℃时试样的能量吸收能力最强,且峰值时效附近的试样能量吸收效率均得到提高,高效阶段更持久;TEM实验结果表明,时效至425℃的泡沫铝试样胞壁中弥散分布着大量细小、共格的二次Al3(Sc,Zr,Ti)相,其粒径为2.1~4.1 nm,这些相能钉扎晶界,阻碍位错运动,因而能显著提高泡沫铝合金的压缩和吸能性能。     

占位法制备球形孔泡沫铝的结构与性能研究

以氯化钙、硬脂酸、硫代硫酸钠、尿素作为造孔剂,利用占位法进行孔径为1～2 mm,孔隙率为60%、70%、80%球形孔泡沫铝的制备。对其孔结构(孔面积、孔圆形度)、压缩性能和吸能效果进行对比分析。结果表明：氯化钙-泡沫铝因其具备较好的孔结构,所表现出的压缩性能和吸能效果也更优异。     

CaCl2作为造孔剂制备泡沫青铜的结构和力学性能

以青铜粉为原料、CaCl_2为造孔剂,采用粉末烧结溶解法制备开孔泡沫青铜。通过改变造孔剂体积分数和粒径成功制备出孔隙率为70%~90%,孔径1~3mm的泡沫青铜试样。研究了孔隙率和造孔剂的关系以及孔隙率、孔径对泡沫试样力学性能的影响,并对其孔结构,相组成和微观形貌进行观察和分析。结果表明:泡沫青铜试样的塑性屈服平台应力随孔隙率增加而减小,当孔隙率为77%~89%时,对应塑性屈服平台应力为12.6~2.6MPa。当应变量为50%时,孔隙率为77%~89%的泡沫青铜单位体积能量吸收值(W)范围为6.21~0.91MJ/m~3。试样的理想吸能效率(I)都接近0.82,说明泡沫青铜可以作为一种理想的吸能材料。     

含Sc、Zr泡沫铝合金的压缩和能量吸收性能

以孔隙率为71.5%~72.5%的泡沫Al-0.16Sc-0.08Zr合金为研究对象(熔体发泡法),研究了等时时效对泡沫铝压缩力学性能和能量吸收性能的影响。结果表明,泡沫铝合金孔多呈球形,孔径约为0.9mm;由于Zr添加量较少,基体中并未发现初生Al3(Zr,Sc)相析出;试样经200~600℃等时时效,随时效温度升高,其压缩强度先增加后降低,时效至400℃的试样压缩屈服强度和能量吸收能力最强;时效处理会导致胞壁塑性下降,影响试样屈服平台过程,其能量吸收效率得到显著提高,且高效阶段更持久。TEM结果表明,等时时效至400℃的试样胞壁中弥散分布着大量纳米级共格Al_3(Sc,Zr,Ti)相,粒径为2.9~4.8nm。这些纳米相能钉扎晶界,阻碍位错运动,改善其压缩和吸能性能。     

球形孔泡沫铝合金压缩性能与理论模型

研究了孔隙率低于65％的球形孔泡沫铝合金的单轴压缩应力应变曲线、吸能能力和吸能效率,并与多面体形孔泡沫铝合金比较,表明球形孔使力学性能有较大提高。采用球形自洽模型研究了球形孔泡沫铝合金的屈服应力与孔隙率关系,与实验结果吻合良好,表明该模型可以有效地预测球形孔泡沫铝合金的屈服强度。     

动态载荷下胞状铝合金的压缩行为

用分段式Hopkison压杆研究了胞状铝合金及胞状纯铝在高应变速率(600～1800s-1)下的压缩行为.试验表明,胞状纯铝的平台应力随应变速率的增大缓慢增加,而胞状铝合金的平台应力对应变速率不敏感,后者在上述应变速率条件下,可以不考虑应变速率的变化,可以静态压缩σ-ε数据作为应用参考.     

变质处理及热处理对泡沫铝合金压缩吸能性的影响

采用可溶石膏型预制块,通过加压渗流的方法制备了高孔隙率的ZL101开孔泡沫铝合金,并对泡沫铝合金进行变质处理和T6热处理.通过压缩试验研究了变质处理和固溶热处理对泡沫铝合金的压缩吸能性能的影响.结果表明,通过石膏型渗流法制备的开孔泡沫铝合金的孔隙率可以达到89.3%～90.7%,采用变质处理和热处理能够有效提高开孔泡沫铝合金的强度,获得高比强度的开孔泡沫铝合金,其比强度达到0.82,理想吸能效率可达85%.     

泡沫镁宏微观结构表征及压缩性能研究

针对熔体发泡法制备泡沫镁存在的困难,使用包覆发泡剂及改进工艺成功制得泡孔均匀的泡沫镁试样。利用OM、SEM、EDS及XRD等分析手段对试样进行宏微观结构表征,结果表明：泡沫镁试样宏观孔以典型的闭孔结构为主,但也存在一些连通孔及少量大孔,它们多是宏观裂纹的产生及扩展位置。泡孔内壁存在一些褶皱缺陷,且弥散分布着许多反应产生的MgO和CaO颗粒,压缩变形过程中,这些部位易产生应力集中,促进微裂纹的形成与扩展。孔壁上主要分布着碳化硅颗粒及生成的Mg2Ca相。测试分析了孔隙率和孔径对泡沫镁压缩力学性能和能量吸收性能的影响,并深入研究其压缩破坏机理,研究发现：随着孔隙率的降低,泡沫镁弹性变形增大,屈服强度升高;随着孔径的增大,泡沫镁屈服强度及平台应力明显减小,表现出显著的孔径效应。随着孔隙率的升高或孔径的增大,泡沫镁的能量吸收性能显著降低。泡沫镁的破坏为解理脆性断裂,这与孔壁组织及镁基体性质有很大的关系。     

泡沫Al合金的压缩性能及其能量吸收

研究了泡沫纯铝和泡沫ＡｌＳｉ７Ｍｇ０．４５在单向压缩条件下的应力－应变（σ－ε）曲线,分析了它们的变形行为,并讨论了其能量吸收和能量吸收效率,结果表明：泡沫纯铝与泡沫Ａｌ合金的σ－ε曲线均由弹性变形段、平缓段和紧实段组成;在压缩过程中,泡沫纯铝的骨架变形以弯曲为主,泡沫ＡｌＳｉ７Ｍｇ０．４５的骨架变形主要由局部断裂产生;在相同孔隙率下,泡沫ＡｌＳｉ７Ｍｇ０．４５的能量吸收大于泡沫纯铝;能量吸收效率     

粉末冶金法制备SiC_p/2024Al泡沫复合材料的表征(英文)

为了丰富泡沫材料制备工艺、推动其快速发展与广泛应用,以CaCO3为发泡剂采用粉末冶金法制备SiCp/2024Al泡沫复合材料。采用SEM和Magiscan-2A图像分析仪研究了CaCO3发泡剂和SiC颗粒的含量对发泡行为的影响,并且通过Gleeble 1500热模拟机分析了SiC颗粒的含量对压缩性能的影响。结果表明:随着发泡剂的增多,孔隙率和孔径先增加后减小。随着增强体含量的增加,孔隙率和孔径都减小。压缩曲线揭示加入增强体可以改善压缩屈服强度和吸能能力。SiCp/2024Al泡沫复合材料显示为脆性泡沫材料。     

Preparation and characterization of SiCp/2024Al composite foams by powder metallurgy

SiC_p/2024Al composite foams were manufactured by powder metallurgical methods using foaming agent CaCO₃ in order to enrich the foam fabrication process and promote its development and extensive application. The effects of CaCO₃ and SiC volume fractions on the foaming behaviours were investigated by means of SEM and Magiscan-2A image analysis technique. The influence of SiC content on the compressive behaviour was analyzed using Gleeble 1500 thermal simulation testing machine. The experimental results show that with increasing the foaming agent, the porosity and pore dimension increase first and decrease later. With increasing the reinforcement content, the porosity and pore dimension decrease. The compressive curves reveal that the introduction of SiC particles can improve compressive yield strength and energy absorption capacity. Meanwhile, it is found that SiC_p/2024Al composite foams are the brittle foam materials.     

Compressive properties of aluminum foams by gas injection method

The compressive properties of aluminum foams by gas injection method are investigated under both quasi-static and dynamic compressive loads in this paper.The experimental results indicate that the defo...     

Compressive and energy absorption properties of closed-cell magnesium foams

The quasi-static compressive mechanical behavior and deformation mechanism of closed-cell magnesium foams were studied, and the effects of the density of magnesium foams on the compressive and energy absorption properties were also discussed. The results show that the compressive process of closed-cell magnesium foams is characterized by three deformation stages: linear elastic stage, collapsing stage and densification stage. At the linear elastic stage, the peak compressive strength (σ ₀) and Young’s modulus (E ₀) increase as the density increases. Magnesium foams can absorb energy at the collapsing stage. In a certain strain range, the energy absorption capacity also increases as the density of magnesium foams increases.     

SiC颗粒对粉末冶金泡沫铝的力学性能影响

本文在SiC颗粒增强粉末冶金泡沫铝压缩试验的基础上,研究SiC颗粒对其力学性能、吸能能力和吸能效率的影响。结果表明:SiC颗粒增强粉末冶金泡沫铝压缩应力应变曲线,呈现线弹性变形、屈服平台阶段、致密化阶段;其屈服强度随SiC颗粒的体积百分含量增大而增大。     

Fabrication and compressive behavior of open-cell aluminum foams via infiltration casting using spherical CaCl2 space-holders

The infiltration casting fabrication process based on spherical CaCl₂ space-holders and the compressive behavior including the mechanical performance and energy absorption capacity of open-cell aluminum foams were investigated.Open-cell aluminum foams with different porosities in the range of 63.1%to 87.3%can be fabricated by adjusting compression ratios of CaCl₂ preforms prepared by precision hot-pressing.The compression tests show that a strain-hardening phenomenon always occurs especially for open-cell aluminum foam with low porosity,resulting in the inclining stress-strain curve in the plateau region.The energy absorption capacity of open-cell aluminum foam decreases with increasing porosity when compared at the same strain.However,when compared at a given stress,each foam can absorb the maximal energy among the five foams in a special stress range.Additionally,open-cell aluminum foam possesses the maximum energy absorption efficiency at its optimum operating stress.At this stress condition,the foam can absorb the highest energy compared with other foams at the same stress point.The optimum operating stress and the corresponding maximal energy absorption decrease with increasing the porosity.The optimum operating stress for energy absorption can also be determined similarly when taking into consideration of the lightweight extent of foams.     

盐球渗透铸造法制备开孔泡沫铝的孔结构及压缩性能

使用圆盘造粒机制备近球形的NaCl颗粒,并将其用于渗透铸造制备开孔泡沫铝。盐球的平均抗压缩强度为3.9 MPa,在超声波清洗机中可在5 min内完全塌陷。通过控制热压烧结时间为0.5～2 h,热压温度700℃,可制备堆积密度在0.66～0.83 g/cm³的预制体。延长热压烧结时间会使开孔泡沫铝的孔径从0.48 mm增加到1.16 mm,孔隙率从64%增加到82%。压缩实验结果表明,不同孔隙结构下泡沫体的宏观变形特征基本相同,均表现出逐层塌陷的变形特征。此外,泡沫铝的致密化应变值、弹性模量、平台屈服应力和能量吸收能力均随着孔隙率的增加而降低。当孔隙率为64%时,能量吸收能力最大(15.0 MJ·m^-3)。     

Compressive characteristics of closed-cell aluminum foams with different percentages of Er element

In the present study, closed-cell aluminum foams with different percentages of erbium(Er) element were successfully prepared. The distribution and existence form of erbium(Er) element and its effect on the compressive properties of the foams were investigated. Results show that Er uniformly distributes in the cell walls in the forms of Al3 Er intermetallic compound and Al-Er solid solutions. Compared with commercially pure aluminum foam, Er-containing foams possess higher micro-hardness, compressive strength and energy absorption capacity due to solid solution strengthening and second phase strengthening effects. Additionally, the amount of Er element should be controlled in the range of 0.10 wt.%-0.50 wt.% in order to obtain a good combination of compressive strength and energy absorption properties.