INTERPRETATION OF HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPE IMAGES OF SHORT-RANGE ORDERED NI4MO

High resolution transmission electron microscope (HRTEM) image contras t of short-range order (SRO) in Ni4Mo alloys has been investigated by means of multi-slice simulations. The HRTEM image contrast of SRO in N i4Mo coincides with a projection contrast of an SRO structure which in volves D1(a), D0(22) and Pt2Mo-type subunit cells in a disordered matr ix. Multi-slice simulations revealed that the SRO structure exhibit a projection contrast in the HRTEM Image when the fundamental fee lattic e reflections contribute sufficiently to HRTEM imaging. The results in dicate that the image of SRO in Ni4Mo can be interpreted in terms of p rojected potential of atomic columns under an appropriate imaging cond ition.