Abstract
The present study addressed the change in the microstructure of Al-2.5 wt％Fe binary alloy produced using laser powder bed fusion(L-PBF)technique by thermal exposure at 300℃,and the associated mechanical and thermal properties were systematically examined as well.Multi-semi-cylindrical pat-terns corresponding to melt pools in the microstructure were macroscopically observed for the as-manufactured sample.No change in the melt-pool morphology was observed after thermal exposure for 1000 h.Inside the melt pools,a large number of the nanoscale metastable Al6Fe phase particles were uniformly distributed inside columnar grains of the α-Al matrix containing concentrated solute Fe in su-persaturation.The sequential formation and coarsening of stable θ-Al13Fe4 phases were observed upon exposure to a 300℃environment,but a considerable amount of nano-sized metastable Al6Fe phases re-mained even after 1000 h.Furthermore,the thermal exposure continuously reduced the concentration of solute Fe atoms in the α-Al matrix.No significant grain growth was found in α-Al matrix after 1000 h owing to the pinning effect of the dispersed fine particles on grain boundary migration.These results demonstrate a sluggish change in microstructural morphologies of the Al-2.5 wt％Fe alloy.The quan-tified microstructural parameters addressed dominant strengthening contributions by the solid solution of Fe element and Orowan strengthening mechanism by fine Al-Fe intermetallics in the L-PBF-produced alloy.The high strength level was sustained even after being exposed to 300℃for long periods.The superior balance of mechanical properties and thermal conductivity can be achieved in the experimental alloys by taking advantage of the various microstructural parameters related to the Al-Fe intermetallic phases and α-Al matrix.
基金项目
a Prior-ity Research Project of the Aichi Prefectural Government(Japan)()
JSPS KAKENHI(20H02462)
fellowship of the China Scholarship Council(201806890005)
NETL
NSTL
万方数据