  Astrometric microlensing can be used to make precise measurements of the
masses of lens stars that are independent of their assumed internal physics.
Such direct mass measurements, obtained purely by observing the gravitational
effects of the stars on external objects, are crucial for validating
theoretical stellar models. Specifically, astrometric microlensing provides a
channel to direct mass measurements of single stars for which so few
measurements exist. To use the astrometric solutions and photometric
measurements of ~1.7 billion stars from Gaia Data Release 2 to predict
microlensing events during the nominal Gaia mission and beyond. This will
enable astronomers to observe the entirety of each event with appropriate
observing resources. The data will allow precise lens mass measurements for
white dwarfs and low-mass main sequence stars helping to constrain stellar
evolutionary models. I search for source-lens pairs in GDR2 that could lead to
events between 25/07/2014 and 25/07/2026. I estimate lens masses using GDR2
photometry and parallaxes, and appropriate model isochrones. Combined with
source and lens parallax measurements from GDR2, this allows the Einstein
radius to be computed for each pair. By considering the paths on the sky, I
calculate the microlensing signals that are to be expected. I present a list of
76 predicted microlensing events. 9 and 5 astrometric events will be caused by
LAWD37 and Stein2051B. 9 events will exhibit detectable photometric and
astrometric signatures. Of the remaining events, ten will exhibit astrometric
signals with amplitudes above 0.5 mas, while the rest are low-amplitude
astrometric events with amplitudes between 0.131 and 0.5 mas. 5 and 2 events
will reach their peaks during 2018 and 2019. 5 of the photometric events have
the potential to evolve into high-magnification events, which may also probe
for planetary companions to the lenses.
