Precipitation　of　dispersive　nanoparticles　has　recently　been　found　to　yield　superfunctional　properties,　such　as　the　large　and　sensitive　magnetostriction　in　body-centered-cubic　(bcc)　Fe-Ga　alloys　with　face-centered-tetragonal　(fct)　nanoprecipitates,　and　applying　this　strategy　to　grain-aligned　alloys　may　allow　one　to　obtain　better　performance.　However,　the　internal　stress　generated　during　directional　solidification　may　alter　the　precipitation　behaviors　by　accelerating　atomic　clustering,　therefore,　a　careful　analysis　of　the　morphology　of　precipitates　and　solute　partitioning　is　needed.　Herein,　we　investigated　the　dynamic　precipitation　behavior　in　a　directionally　solidified　Fe73Ga27　alloy　with　[001]　orientation.　Through　comparisons　with　random　polycrystalline　sample　subjected　to　the　same　aging　treatment,　we　find　that　the　[001]-oriented　sample　produces　sparser　fct　nanoprecipitates　and　extra　interfacial　omega　nanoprecipitates.　The　internal　stress　accelerates　Ga　partitioning　between　the　fct　nanoprecipitates　and　the　matrix,　hence　reducing　their　nucleation　sites.　The　internal　stress　also　alters　the　mutual　elastic　interactions　between　matrix　and　precipitates,　where　the　Bain　strains　of　fct　nanoprecipitates　are　mostly　accommodated　by　forming　Ga-enriched　omega　nanoprecipitates　and　{112}　stacking　faults　at　the　phase　front,　unlike　that　for　random　polycrystalline　sample,　where　the　Bain　strains　are　accommodated　by　local　tetragonal　distortion　of　the　matrix.　As　a　result,　the　magnetostriction　enhancement　ratio　is　40%　for　the　grain-aligned　sample,　weaker　than　~165　%　for　the　random　polycrystalline　sample.　Our　results　not　only　shed　lights　on　the　precipitation　difference　between　stress-containing　and　stress-free　aging　conditions　but　also　help　to　guide　the　microstructure　design　of　superfunctional　alloys　in　which　the　type,　number　density　and　size　of　nanoprecipitates　should　be　carefully　controlled.　©　2021