The SKPFM Volta potential distribution maps (Fig. ) showed very different potential responses within the studied alloys supporting the assumptions made in the analysis of the SEM/EDX data. In the case of AZ31-4Li alloy (Fig. ), some intermetallic particles were clearly visible in the microstructure with values of the contact potential difference up to 100 mV compared to the alloy matrix. In the AFM setup configuration the signal is obtained by a nulling method in a way that lower values of the contact Volta potential difference given by the instrument indicate more electrochemically "noble" materials . When interpreting these results one should bear in mind that signal inversion was not performed in this study, consistent with previous conventions . Therefore, these regions are assigned to Al-and Mn-rich IMPs, which in the corrosion process will serve as cathodic sites promoting local corrosion attack of the Mg matrix phase around them. In the periphery of the larger IMP (profile 1 in Fig. ), there was a small region with up to ca. 30 mV larger contact Volta potential difference compared to the alloy matrix, indicating its relative anodic response. This region, most probably, was rich in Li and Mg.