화학공학소재연구정보센터
Materials Science Forum, Vol.386-3, 559-564, 2002
On the atomic force microscopy characterization of some Zr-based metallic glasses: Anomalous electrostatic behavior
Contact mode of an atomic force microscopy has been used to measure the forces between a Si3N4 tip mounted on a cantilever beam and a virgin surface of Zr60-xNi10Cu20Al10Pdx (x = 0 and 5 at%) and Zr65Ni10Cu7.5Al7.5Pd10 metallic glass forming alloys as function of the tip-surface separation. Previously, it was established that both nanocrystalline and crystalline states of Zr60Ni10Cu20Al10 bulk metallic glass exibit higher interaction potential. However, an excess electrostatic, Van der Waals and adhesive interactions above the usual magnitude recorded is observed in samples containing Pd as solute component and increases with increasing Pd content. While Pd is known to promote the precipitation of nano-scaled icosahedral metastable phase in the selected alloy, Pd40Cu30Ni10P20 metallic glass sample exhibits also high electrostatic interactions. This excess vanishes during the reverse process to return to equilibrium state. Both relative variation of normal and lateral force component were recorded at different scan size ranging from 10 mum down to several nanometers and a maximum load of few micro-Newton. Moreover, differential scanning calorimetry analysis and x-ray diffraction characterizations were conducted in conjunction with AFMs series. A correlation between the lateral, normal forces, adhesion hysterisis loops of the microstructures investigated and the strength of their instantaneous dipole interaction is developed.