【摘要】 以Ni-15Cr合金、Fe₂O₃粉末和金属钇为原材料，在直接铸造法、底部铺粉法、熔体冲刷法等3种Fe₂O₃氧载体加入方式下采用氧载体熔铸法制备氧化物弥散强化（ODS）镍基合金，研究了氧载体加入方式和钇加入量（质量分数0.1%,0.2%,0.3%，对应Fe₂O₃质量分别为1.8,3.6,5.4 g）对合金凝固组织以及第二相颗粒宏观均匀性的影响。结果表明：采用3种氧载体熔铸法均成功在镍基合金中制备出由Y₂O₃和Y-Al-O复杂氧化物组成的亚微米级（<1μm）及微米级（1～7μm）第二相颗粒（Y&O颗粒）。钇与氧载体的加入使合金等轴晶平均晶粒尺寸降低约67%，同时完全消除了合金中的Al₂O₃-Cr₂O₃夹杂物，晶内及晶界处形成大量富钇相；随钇加入量增加，富钇相增多，晶界处富钇相由链状转变为网状结构。氧载体加入方式和钇加入量对Y&O颗粒尺寸影响不大。在相同钇加入量条件下，直接铸造法制备合金中Y&O颗粒的平均体数密度最小，底部铺粉法次之，熔体冲刷法最大。随着钇加入量增加，熔体冲刷法制备合金中的Y&O颗粒体数密度下降。直接铸造法制备的铸锭上部Y&O颗粒最多；底部铺粉法制备的铸锭中Y&O颗粒由下至上减少；熔体冲刷法制备的铸锭则呈现上、下部颗粒多而中部少的分布特征。3种氧载体加入方式均难以制备出Y&O颗粒均匀弥散分布的ODS镍基合金。更多还原

【Abstract】 Using Ni-15 Cr alloy,Fe₂O₃ powder,and metallic yttrium as raw materials,oxide dispersion strengthened（ODS） nickel-based alloys were prepared by the oxygen carrier melt casting method under three Fe₂O₃ oxygen carrier addition modes（direct casting,bottom powder laying,and melt flushing）. The effects of the oxygen carrier addition mode and yttrium addition amount（mass fraction of 0.1%, 0.2%, 0.3%, corresponding to Fe₂O₃ masses of 1.8, 3.6, 5.4 g,respectively） on the solidification structure and macroscopic uniformity of the second phase particles of the alloy were investigated. The results show that submicron-sized（<1 μm） and micron-sized（1–7 μm） second phase particles（Y&O particles） composed of Y₂O₃ and Y-Al-O complex oxides were successfully prepared in the nickel-based alloy by three oxygen carrier melt casting methods. The addition of yttrium and oxygen carrier reduced the average equiaxed grain size of the alloy by about 67%,while completely eliminating Al₂O₃-Cr₂O₃ inclusions in the alloy,and forming numerous yttriumrich phases within the grains and at grain boundaries. With increasing yttrium addition,the yttrium-rich phases increased,and the morphology at grain boundaries transformed from a chain-like structure to a network structure. The addition mode of oxygen carrier and the yttrium addition amount had little effect on the size of Y&O particles. Under the same yttrium addition amount,the average number density of Y&O particles was the smallest in the alloy prepared by direct casting,followed by bottom powder laying,and the largest in the alloy prepared by melt flushing. With increasing yttrium addition amount,the number density of Y&O particles in the alloy prepared by melt flushing decreased. The upper part of the ingot prepared by the direct casting had the most Y&O particles. The Y&O particles in the ingot prepared by the bottom powder laying decreased from bottom to top. The ingot prepared by the melt flushing showed a distribution feature with more particles in the upper and lower parts and fewer in the middle. None of the three oxygen carrier addition modes could produce an ODS nickel-based alloy with uniformly and homogeneously dispersed Y&O particles.更多还原