Dynamics of Crack Healing and its Molecular Dynamics Simulation of Al₂O₃-MgAlON Composite

Abstract:

After preparing samples (3mm long×4mm wide×36mm high) of Al2O3-MgAlON composites and sintered at 1500°C for 2 h in N2 atmosphere, samples’ cracks were carved by a Vickers hardometer’s pressing head on the center of the sample surface (4 mm×36 mm). Subsequently, the cracks were healed at 1000°C-1550°C for 6 h respectively. Effects of healing temperature on sample’s strength, crack healing dynamics and its molecular dynamics simulation were investigated. The results suggested that: the optimum range of cracks healing temperature was 1300°C-1550°C, and the healing process accelerated at 1300°C, meanwhile, the strength of samples increased significantly. Cracks completely healing finished at 1550°C. The dynamics equation of crack healing was lnν = -Q/kT+lnC. Through characterizing the crack healing rate with the recovering rate of sample’s strength, the diffusion activation energy Q = 4.264 × 10-30 J•K-1 and diffusion constant C=7.359 were claimed. The result of the molecular dynamics simulation suggested that cracks healing process was caused by diffusion could be divided into five stages: passivation of crack tips, formation of salient island, crack shrinkage, generation of secondary crack, and complete healing.

• Periodical: Advanced Materials Research (Volumes 105-106)
• Pages: 137-141
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.105-106.137
• Online since: April 2010
• Authors: Dao Yuan Yang, Hui Yu Yuan, Fen Ling Qian, Juan Wu, Kai Zhu, Rui Zhang
• Keywords: Al₂O₃-MgAlON Composite, Crack Healing, Molecular Dynamic Simulation

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