A　martensitic　transformation　from　the　a　to　the　gamma　phase　of　aluminum　oxide　was　observed　by　transmission　electron　microscopy　(TEM)　upon　rapid　heating　induced　by　pulsed　laser　irradiation.　Two　variants　possessing　a　twin　relationship　were　found　in　the　product.　High-resolution　TEM　reveals　that　the　transformation　is　achieved　via　the　glide　of　quarter　partial　dislocations　on　every　other　basal　plane　of　alpha-Al2O3.　The　high　thermal　stress　caused　by　pulsed　laser　irradiation　is　believed　to　be　the　main　driving　force　of　the　phase　transformation.　This　martensitic　transformation　is　associated　with　a　positive　volume　change　and　substantial　shear　strain.　The　overall　shear　strain　could　be　minimized　by　the　self-accommodating　variants.　These　characteristics　suggest　potential　application　of　the　martensitic　transformation　for　transformation　toughening　in　ceramic　materials.　(C)　2010　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.