Prior to phase imaging, all probes were characterized by a blind tip reconstruction method using a niobium roughness sample (RS from Bruker). The scan rate (lines/s) was determined based on matching the sampling rate (pixels/s) to the ratio between resonant frequency and quality factor, both measured by GetReal TM function. All images were taken at a resolution of 128x128 pixels, with the ROI adjusted to encompass the interphase thickness. The retract portion of force curves were fit with the JKR model using the MagicAFM software of Sheridan, et al. Further information about the phase map analysis is summarized in the SI.