  Gallium oxide with a corundum structure ({\alpha}-Ga2O3) has recently
attracted great attention in view of electronic and photonic applications due
to its unique properties including a wide band gap exceeding that of the most
stable beta phase (\b{eta}-Ga2O3). However, the lower thermal stability of the
{\alpha}-phase at ambient conditions in comparison with the \b{eta}-phase
requires careful investigation of its resistance to other external influences
such as ion irradiation, ion doping, etc. In this work, the structural changes
under the action of Al+ ion irradiation have been investigated for a
polymorphic gallium oxide layers grown by hydride vapor phase epitaxy on
c-plane sapphire and consisting predominantly of {\alpha}-phase with inclusions
of {\alpha}(\k{appa})-phase. It is established by the X-ray diffraction
technique that inclusions of {\alpha}(\k{appa})-phase in the irradiated layer
undergo the expansion along the normal to the substrate surface, while there is
no a noticeable deformation for the {\alpha}-phase. This speaks in favor of the
different radiation tolerance of various Ga2O3 polymorphs, especially the
higher radiation tolerance of the {\alpha}-phase. This fact should be taken
into account when utilizing ion implantation to modify gallium oxide properties
in terms of development of efficient doping strategies.
