Compression‐compression fatigue performance of aluminium matrix composite foams reinforced by carbon nanotubes

Abstract

The compression‐compression fatigue performance of carbon nanotube (CNT) reinforced aluminium matrix composite foams (AMCFs) were investigated. The ε‐N curves of AMCFs are composed of three stages (the elastic, strain hardening, and rapid accumulation stages), while the fatigue strain of AMCFs accumulates very rapidly in stage III compared with Al foams. The fatigue strength of AMCFs with CNT contents of 2.0, 2.5, and 3.0 wt% increases by 6%, 44%, and 102% than Al foams, respectively. Different from Al foams' deformation of layer‐by‐layer, the main failure modes of AMCFs are the brittle fracture and collapse of pores within significant shear deformation bands under fatigue loading. The uniform distribution of CNTs and good interfacial bonding of CNTs and Al matrix is the important factor for the improvement of fatigue properties of AMCFs.

Controllable Design of Structural and Mechanical Behaviors of Al–Si Foams by Powder Metallurgy Foaming

“…The stress–strain curves (Figure 7a) show three typical regions. [ 5,9,34 ] Likewise, the deformation behavior of Al–Si foams normally has three stages, elastic deformation stage, plastic/brittle deformation stage, and collapse deformation stage, which is correlated with cellular failure. All the deformation processes are dependent on two especial elements: densification strains and plateau stress, which could be characterized by Equation () and ().…”

“…For Al–Si foams, yield stress and plateau tress represent the first peak stress and average stress of plateau region. [ 5,9 ] The densification strain is regarded as the maximum energy absorption capacity of Al–Si foams, where the energy absorption capacity could be expressed by Equation (). …”

“…[1][2][3][4][5][6][7][8] Especially, the closed-cell Al foams, which are typically fabricated through three manufacturing methods: gas injection method, melt foaming (MF) method, and powder metallurgy foaming (PMF) method, exhibit not only lightweight property, but also excellent strength, stiffness, and impact energy absorbing capacity when subjected to external loads. [9][10][11][12][13][14] It is known that the energy absorption capacity of Al foams is mainly determined by the cellular structure and matrix properties. [11,15] However, the intrinsic restrictions of physical metallurgical characteristics and mechanical properties of Al foams hinder the industrial applications for engineering components.…”

Effect of Heat Treatment on the Microstructure, Compressive Property, and Energy Absorption Response of the Al–Mg–Si Alloy Foams

“…All the stress-strain curves are found to exhibit a slight "stress drop" characteristic, which is mainly caused by the cellular pore structure instability. [31][32][33][34] Generally, before the peak stress, most of the cell walls and struts will undergo a complicated processing of buckling, bending, and tearing. [27] When the porous material reaches the peak stress, a part of the pore walls will be instantly destabilized and lead to a drop of the compression stress.…”

“…[27] When the porous material reaches the peak stress, a part of the pore walls will be instantly destabilized and lead to a drop of the compression stress. [15,32] Subsequently, the cell walls will fill the pores and contact with each other, and after the cell walls are fully compacted, the compressive stress will rapidly increase. It should be noted that compared with the Al alloy foams that are fabricated by the melt foaming method, [35,36] the plateau region of the Al-Mg-Si alloy foams in this article displays a much slighter characteristic instead of severe fluctuations.…”