A silicon crystal amorphized with 80 keV Fe ions and later implanted with 620 MeV Pb ions was investigated by HRTEM and by X-ray diffraction methods. HRTEM reveals crystal defects at about 20 mm depth. Tracks which could be formed by Pb ions were not found. It is shown that the X-ray rocking curve has components coming from less distorted and distorted layers. Experimental results are compared with those obtained by TRIM simulation procedure.