目的通过机械合金化与热压烧结相结合的方法制备含有B2结构纳米NiAl相的铁基合金,研究不同含量(质量分数为30%、40%、50%、60%)的纳米NiAl相,对合金显微组织及力学性能的影响。方法以Ni粉和Al粉为原材料,通过高能球磨法制备B2结构纳米N...目的通过机械合金化与热压烧结相结合的方法制备含有B2结构纳米NiAl相的铁基合金,研究不同含量(质量分数为30%、40%、50%、60%)的纳米NiAl相,对合金显微组织及力学性能的影响。方法以Ni粉和Al粉为原材料,通过高能球磨法制备B2结构纳米NiAl粉体,采用真空热压烧结炉将NiAl粉体与Fe粉混合烧结,得到块体试样。采用扫描电镜(Scanning electron microscopy,SEM)进行微观组织观察,采用能谱仪(Energy dispersive spectroscopy,EDS)、X射线衍射仪(X-ray diffraction,XRD)以及透射电子显微镜(Transmission electron microscopy,TEM)进行物相分析,并测试不同NiAl含量的铁基合金的硬度、密度、室温压缩性能以及600℃的抗氧化性能。结果合金的硬度、抗压强度随NiAl含量先增后降。当NiAl的质量分数为50%时,合金硬度为35.2HRC,抗压强度为2530MPa,密度为6.68g/cm^3,较未添加NiAl时,合金的抗压强度提升了239.6%,密度降低了14.5%。θ=600℃、t=1200min时,其表面氧化增重较纯铁降低了37.9%,此时NiAl相的尺寸约为100~200nm,组织最为均匀,致密度较高。结论纳米NiAl相在降低铁基合金密度的同时,能有效提升其力学性能与抗氧化性能,但由于B2结构的纳米NiAl相为一种硬脆相,当其含量过高时,会极大程度地降低合金的力学性能。展开更多
The isothermal oxidation behavior of Ni_3Al containtng 15 at.% Fe and NiAl containing 30 at.% Fe was studied for 100 h at 850, 950, 1050 and 1150℃, respectively. The results show that the oxidation kinetics of the tw...The isothermal oxidation behavior of Ni_3Al containtng 15 at.% Fe and NiAl containing 30 at.% Fe was studied for 100 h at 850, 950, 1050 and 1150℃, respectively. The results show that the oxidation kinetics of the two alloys obey a parabolic law at various temperatures and every parabolic curve possesses two oxidation rate constants. The morphology, microstructure and the chemical composition of the oxide scales were examined using optical metallography, X-ray diffraction analysis, scanning electron microscopy and electron probe microanalysis. The oxide scale of Ni_3Al containing 15 at.% Fe consists mainly of NiO, NiFe_2O_4, and FeAl_2O_4, and that of NiAl containing 30 at.% Fe consists of Fe_2O_3 and (Fe,Ni)Fe_2O_4, contrasting sharply to the oxide scales of pure Ni_3Al and NiAl which consist of Al_2O_3. The oxide scales on the surfaces of Ni_3Al and NiAl containing Fe are not too dense and not too cohesive to the matrix,so their oxidation resistance is not too good.展开更多
文摘目的通过机械合金化与热压烧结相结合的方法制备含有B2结构纳米NiAl相的铁基合金,研究不同含量(质量分数为30%、40%、50%、60%)的纳米NiAl相,对合金显微组织及力学性能的影响。方法以Ni粉和Al粉为原材料,通过高能球磨法制备B2结构纳米NiAl粉体,采用真空热压烧结炉将NiAl粉体与Fe粉混合烧结,得到块体试样。采用扫描电镜(Scanning electron microscopy,SEM)进行微观组织观察,采用能谱仪(Energy dispersive spectroscopy,EDS)、X射线衍射仪(X-ray diffraction,XRD)以及透射电子显微镜(Transmission electron microscopy,TEM)进行物相分析,并测试不同NiAl含量的铁基合金的硬度、密度、室温压缩性能以及600℃的抗氧化性能。结果合金的硬度、抗压强度随NiAl含量先增后降。当NiAl的质量分数为50%时,合金硬度为35.2HRC,抗压强度为2530MPa,密度为6.68g/cm^3,较未添加NiAl时,合金的抗压强度提升了239.6%,密度降低了14.5%。θ=600℃、t=1200min时,其表面氧化增重较纯铁降低了37.9%,此时NiAl相的尺寸约为100~200nm,组织最为均匀,致密度较高。结论纳米NiAl相在降低铁基合金密度的同时,能有效提升其力学性能与抗氧化性能,但由于B2结构的纳米NiAl相为一种硬脆相,当其含量过高时,会极大程度地降低合金的力学性能。
文摘The isothermal oxidation behavior of Ni_3Al containtng 15 at.% Fe and NiAl containing 30 at.% Fe was studied for 100 h at 850, 950, 1050 and 1150℃, respectively. The results show that the oxidation kinetics of the two alloys obey a parabolic law at various temperatures and every parabolic curve possesses two oxidation rate constants. The morphology, microstructure and the chemical composition of the oxide scales were examined using optical metallography, X-ray diffraction analysis, scanning electron microscopy and electron probe microanalysis. The oxide scale of Ni_3Al containing 15 at.% Fe consists mainly of NiO, NiFe_2O_4, and FeAl_2O_4, and that of NiAl containing 30 at.% Fe consists of Fe_2O_3 and (Fe,Ni)Fe_2O_4, contrasting sharply to the oxide scales of pure Ni_3Al and NiAl which consist of Al_2O_3. The oxide scales on the surfaces of Ni_3Al and NiAl containing Fe are not too dense and not too cohesive to the matrix,so their oxidation resistance is not too good.
