共查询到20条相似文献,搜索用时 510 毫秒
1.
2.
3.
4.
5.
6.
通过累积叠轧法制备泡沫铝.采用称重法研究泡沫铝孔隙结构,利用光学显微镜观察泡沫铝孔隙形貌.发现以TiH2为发泡介质,当发泡温度660~680℃和发泡时间6~10 min时,利用累积叠轧法制备泡沫铝的孔隙结构特性最好.发泡温度和发泡时间的最佳值与发泡剂用量有关,TiH2质量分数为1.5%,在670℃发泡8 min,泡沫铝的孔隙率可达到42%,孔径为0.43 mm.以制备的泡沫铝为夹芯,通过轧制复合制备了TC4钛合金/泡沫铝芯和1Cr18Ni9Ti不锈钢/泡沫铝芯三明治板.利用光学显微镜和能谱仪研究了三明治板的界面.面板与芯板间的化合反应形成了界面的反应层,界面实现了冶金结合. 相似文献
7.
8.
9.
YING CHENG YANXIANG LI XIANG CHEN TONG SHI ZHIYONG LIU NINGZHEN WANG 《Metallurgical and Materials Transactions B》2017,48(2):754-762
This article introduces an improvement to the fabrication of aluminum foams with small pore size by melt foaming method. Before added to the melt, the foaming agent (titanium hydride) was pretreated in two steps. It firstly went through the traditional pre-oxidation treatment, which delayed the decomposition of titanium hydride and made sure the dispersion stage was controllable. Then such pre-oxidized titanium hydride powder was mixed with copper powder in a planetary ball mill. This treatment can not only increase the number of foaming agent particles and make them easier to disperse in the melt, which helps to increase the number of pores, but also reduce the amount of hydrogen released in the foaming stage. Therefore, the pore size could be decreased. Using such a ball-milled foaming agent in melt foaming method, aluminum foams with small pore size (average size of 1.6 mm) were successfully fabricated. 相似文献
10.
11.
Ying Cheng Yanxiang Li Xiang Chen Zhiyong Liu Xu Zhou Ningzhen Wang 《Metallurgical and Materials Transactions B》2018,49(3):1014-1021
Compared to traditional pore structure with high porosity (≥ 80 pct) and large pore size (≥ 3 mm), aluminum foams with low porosity (60 to 70 pct) and small pore size (≤ 2 mm) possess higher compressive property and formability. In order to achieve the goal of reducing pore size, Cu-TiH2 composite powder prepared by ball milling preoxidized TiH2 with Cu powder was used as a blowing agent. Its gas release behavior was characterized by thermogravimetric analysis and differential scanning calorimetry. The results show that the ball milling treatment can advance the gas release process and slow the gas release rate at the same time. All these changes are favorable to the reduction of porosity and pore size. Such Cu-TiH2 composite powder provides an alternative way to fabricate aluminum foams with low porosity and small pore size. 相似文献
12.
G. S. Vinod Kumar M. Mukherjee F. Garcia-Moreno J. Banhart 《Metallurgical and Materials Transactions A》2013,44(1):419-426
We developed a novel process for foaming aluminum and its alloys without using a blowing agent. The process involves a designated apparatus in which molten aluminum and its alloys are first foamed under reduced pressure and then solidified quickly. Foaming was done for pure aluminum (99.99 pct) and AlMg5 alloy not containing stabilizing particles and AlMg5 and AlSi9Mg5 alloys containing 5 vol pct SiO2 particles. We discuss the foaming mechanism and develop a model for estimating the porosity that can be achieved in this process. The nucleation of pores in foams is also discussed. 相似文献
13.
H. Toda T. Kobayashi M. Niinomi T. Ohgaki M. Kobayashi N. Kuroda T. Akahori K. Uesugi K. Makii Y. Aruga 《Metallurgical and Materials Transactions A》2006,37(4):1211-1219
Synchrotron X-ray microtomography has been used for the three-dimensional characterization of microstructure in the cell walls
of aluminum foams. A combination of high-resolution phase contrast imaging technique and several application techniques has
enabled the quantitative image analyses of microstructures as well as the assessment of their effects on deformation behaviors.
The application techniques include local area tomography, microstructural gauging and in-situ observation using a specially designed material test rig. It has been clarified that ductile buckling of a cell wall occurs
regardless of any of the microstructural factors in the case of a pure aluminum foam, while rather brittle fracture of a cell
wall is induced by the existence of coarse micropores and their distribution independently of the intermetallic particles
and the grain boundary in the case of aluminum foams alloyed with Zn and Mg. It has also been confirmed that coarse TiH2 particles, which are a residual foaming agent added to alloy melts, remain intact during the deformation. When cooling rate
during foaming is high, however, lower energy absorption might be attributable to the significant amount of residual TiH2 particle and its inhomogeneous distribution. These tendencies are also confirmed by three-dimensional strain mapping by tracking
internal microstructural features. 相似文献
14.
Yeong Hwan Song Masakazu Tane Takuya Ide Yoshihiro Seimiya Bo Young Hur Hideo Nakajima 《Metallurgical and Materials Transactions A》2010,41(8):2104-2111
Al-3.7 pct Si-0.18 pct Mg foams strengthened by AlN particle dispersion were prepared by a melt foaming method, and the effect
of foaming temperature on the foaming behavior was investigated. Al-3.7 pct Si-0.18 pct Mg alloy containing AlN particles
was prepared by noncompressive infiltration of Al powder compacts with molten Al alloy in nitrogen atmosphere, and it was
foamed at different foaming temperatures ranging from 1023 to 1173 K. The porosity of prepared foam decreases and the pore
structure becomes homogeneous with increasing foaming temperature. When the foaming temperature is higher than 1123 K, homogeneous
pores are formed in the prepared ingot without using oxide particles and metallic calcium granules, which are usually used
for stabilizing a foaming process. This stabilization of the foaming at high temperatures is possibly caused by Al3Ti intermetallic compounds formed at high temperature and AlN particles. Compression tests for the prepared foams revealed
that the absorbed energy per unit mass of prepared Al-3.7 pct Si-0.18 pct Mg foam is higher than those of aluminum foams strengthened
by alloying or dispersion of reinforcements. It is remarkable that the oscillation in stress, which usually appears in strengthened
aluminum foams, does not appear in the plateau stress region of the present Al-3.7 pct Si-0.18 pct Mg foam. The homogeneity
in cell walls and pore morphology due to the stabilization of pore formation and growth by AlN and Al3Ti particles is a possible cause of this smooth plateau stress region. 相似文献
15.
Aluminum foam is a newly developed mobile and lightweight material with excellent energy absorption capacities. Applying aluminum foam as a sacrificial protection layer on the bearing faces of protected structures can mitigate blast effects on the resistance capacities of structures against impact or blast loading. The aluminum foam undergoes great plastic deformation under transient dynamic loads before becoming fully densified, making it excellent for mitigating blast effects on these structures. In this paper, we conducted quasi-static testing on two types of aluminum foam specimens and obtained the primary parameters for the mechanical properties of aluminum foam specimens. We then used these two types of aluminum foams to protect the reinforced concrete (RC) slabs, and we conducted a series of tests to investigate the performance of the aluminum foam–protected RC slabs against blast loads. We tested a total of five foam-protected slabs and one control RC slab in the blast test program. The test results, including displacement and acceleration histories, performance of specimens, and maximum and permanent deflections, were fully reported. We then discussed the efficiency of aluminum foam to mitigate blast loads on protected RC slabs. 相似文献
16.
Dehi Pada Mondal Manmohan Dass Goel Vartika Upadhyay Satyabrat Das Mulayam Singh Ajay Kumar Barnwal 《Transactions of the Indian Institute of Metals》2018,71(3):567-577
In order to examine the effect of microballoons type on microstructure and compressive deformation behaviour of aluminum syntactic foam, alumina reinforced and cenosphere reinforced aluminum syntactic foams have been made through stir-casting technique. Alumina microballoons reinforced aluminum syntactic foam (AMRASF) has been developed using stir casting technique. Volume fraction of alumina microballoons in AMRASF varies in the range of 0.39–0.74. The compressive deformation behavior of these AMRASF is compared with that of cenosphere reinforced aluminum syntactic foam (CPRASF). The AMRASF does not exhibit clear plastic collapse stage as observed in case of CPRSAF. It is further noted that AMRASF shows the existence of work hardening phenomena after yielding but CPRASF does not show any significant work hardening after yielding even at higher relative densities of foam. This is explained on the basis of characteristics of alumina microballoons and cenospheres and interface characteristics between matrix and respective microballoons used. Effect of individual microballoons’ characteristics on the foam properties has also been explained. 相似文献
17.
Lydia Y. Aguirre-Perales In-Ho Jung Robin A.L. Drew 《Metallurgical and Materials Transactions A》2012,43(1):1-5
The study of the dehydrogenation process of TiH2 in aluminum foams produced by the powder metallurgy technique is essential to understanding its foaming behavior. Tin was
added to the Al foam to modify the dehydrogenation process and stabilize the foam. A gradual decomposition and more retention
of hydrogen gas can be achieved with Sn addition resulting in a gradual and larger expansion of the foam. 相似文献
18.
In the powder compact melting technique, metallic foams are fabricated by heating a precursor, thus initiating cell growth
and foam formation. Proper precursor fabrication is very important because the density distribution after foaming and the
foamability are determined during the precursor-fabrication process. The fabrication of the precursor has to be performed
very carefully because any residual porosity or other defects will lead to poor results in further processing. In order to
evaluate the effect of the compaction parameters on the kinetics of the foaming process, a series of experiments were performed.
In this study, 6061 aluminum foams having a closed-cell structure were fabricated by the powder compact method and an induction
heating process. An induction coil was designed to obtain a uniform temperature distribution over the entire cross-sectional
area of the precursor. To establish the foamable precursor fabrication conditions, the effects of process parameters such
as titanium hydride content (0.1 to 1.5 wt pct) and the compression pressure of the foamable precursor (50 to 150 kN) on the
pore morphology were investigated. 相似文献
19.
20.
Gasarites are a subclass of metallic foams that have a cylindrical pore morphology created by directional solidification of metals saturated with a gas. Thermal decomposition is an alternative process in which the soluble gas is delivered by decomposition of a particulate gas source. Aluminum gasarites formed through decomposition of titanium and zirconium hydrides were studied to both replicate the results of a previous study and discern pore-formation mechanisms. Replication of the previous study was not achieved, and additional processing enhancements were required to produce gasarite pore morphologies. For the first time, zirconium hydride was utilized to produce gasarites, with porosity levels and pore sizes lower than that from titanium hydride. Maximum average porosity levels of 10 and 6 pct were observed for titanium hydride and zirconium hydride, respectively. Pore-formation mechanisms in aluminum gasarite foams created via thermal decomposition of titanium and zirconium hydrides were evaluated through metallographic analysis and scanning electron microscopy. Definitive evidence of gas–metal eutectic pore growth was not found, but pore morphological characteristics and chemical analysis of particulate at pore surfaces support direct gas evolution from the hydride particles as a contributor to pore formation and growth. 相似文献