Effects of porosity on tensile mechanical properties of porous FeAl intermetallics
(1. School of Civil Engineering, Central South University, Changsha 410075, China;
2. School of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China;
3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
2. School of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China;
3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract: Uniaxial tensile tests and scanning electron microscopy (SEM) experiments were carried out on the porous FeAl intermetallics (porosities of 41.1%, 44.2% and 49.3%, pore size of 15-30 μm) prepared by our research group to study the macroscopic mechanical properties and microscopic failure mechanism. The results show that the tensile σ-ε curves of the porous FeAl with different porosities can be divided into four stages: elasticity, yielding, strengthening and failure, without necking phenomenon. The elastic modulus, ultimate strength and elongation decrease with the increase of porosity and the elongation is much lower than 5%. A macroscopic brittle fracture appears, and the microscopic fracture mechanism is mainly intergranular fracture, depending on the Al content in the dense FeAl intermetallics. In addition, the stochastic porous model (SPM) with random pore structure size and distribution is established by designing a self-compiling generation program in FORTRAN language. Combined with the secondary development platform of finite element software ANSYS, the effective elastic moduli of the porous FeAl can be determined by elastic analysis of SPM and they are close to the experimental values, which can verify the validity of the established SPM for analyzing the elastic properties of the porous material.
Key words: porous FeAl intermetallics; uniaxial tensile; fracture mechanism; stochastic porous model (SPM); equivalent elastic modulus