Fracture toughness KIC plays an important role in materials design. Along with numerous experimental methods to measure fracture toughness of materials, its understanding and theoretical prediction is very important. However, theoretical prediction of fracture toughness is challenging. By investigating the correlation between fracture toughness and elastic properties of materials, we have constructed a fracture toughness model for covalent and ionic crystals. Furthermore, by introducing an enhancement factor, which is determined by the density of states at the Fermi level and atomic electronegativities, we have constructed a universal model of fracture toughness for covalent and ionic crystals, metals and intermetallics. The predicted fracture toughnesses are in good agreement with experimental values for a series of materials. All the parameters in the proposed model of fracture toughness can be obtained from first-principles calculations, which makes it suitable for practical applications.

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The lower pressure tendency in chemical mechanical polishing (CMP) process requires a lower adhesive inhibitor with environmentally friendly corrosion properties to replace the conventional benzotriazole (BTA) inhibitor for aluminum (Al) CMP. Open circuit potential test, potentiodynamic polarization curve test, linear sweep voltammetry and potential drop investigated by in-situ electrochemical mechanical polishing (ECMP) platform were used to reveal the controlled evolution process of corrosion inhibitor films at low pressure during Al CMP. The comparison between BTA and 1,2,4-triazole (TAZ) shows that TAZ has lower current density, wider potential inhibition interval, and high planarization efficiency, although TAZ has lower adhesion on Al surface. Finally, the surface roughness of Al after CMP with TAZ in weakly alkaline slurry at pressure of 1 psi was observed by atomic force microscopy (AFM) with a value of 0.19 nm. This studies demonstrated that the conventional BTA can be replaced by environmentally friendly corrosion inhibitor TAZ, which is a promising alternative candidate to the Al CMP at low down pressure.

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