Effects of Different Substrates on Microstructures and Mechanical Properties of a Bulk Nanocrystalli

• 作 者: Xiao-juan ZHEN Pei-qing LA Cui-ling LI Su-lei HU
• 机 构: State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,Lanzhou University o
• 出 处: Journal of Iron and Steel Research(International)
• 发表日期: 2015年04期
• 关键词: nanocrystalline aluminothermic reaction casting pure iron substrate microstructu

A simple method was developed to produce the nanocrystalline pure iron by aluminothermic reaction casting.The microstructure of the iron was investigated by optical microscope(OM),transmission electron microscope(TEM),electron probe micro-analyzer(EPMA),scanning electron microscope(SEM)and X-ray diffraction(XRD).The mechanical performances of nanocrystalline pure iron were tested.It is found that the pure iron consists of nanocrystalline ferrite.For different substrates of copper and glass,the average grain size of the ferrite was 38 and 35 nm,respectively,which is larger on copper substrate than that on glass.The hardness,compressive strength,tensile strength,and total elongation are 167 and 137HB,400 and 500MPa,243 and 185MPa,16%and10% on copper substrate and glass substrate,respectively.The hardness,tensile strength and total elongation are all larger on copper substrate than those on glass substrate,while the compressive strength is lower.The large supercooling in the product solidification provides the condition for high nucleation rate and thus leads to nano-grained austenite and final nano-grained ferrite transformed from those small austenite grains.

A simple method was developed to produce the nanocrystalline pure iron by aluminothermic reaction casting. The microstructure of the iron was investigated by optical microscope (OM), transmission electron microscope (TEM), electron probe micro-analyzer (EPMA), scanning electron microscope SEM) and X-ray diffraction (XRD). The mechanical performances of nanocrystalline pure iron were tested. It is found that the pure iron consists of nanocrystalline ferrite. For different substrates of copper and glass, the average grain size of the ferrite was 38 and 35 nm, respectively, which is larger on copper substrate than that on glass. hardness, tensile strength, and total elongation are 167 and 137 HB, 400 and 500 MPa, 243 and 185 MPa, 16% and 10% on copper substrate and glass substrate, respectively. hardness, and total elongation are all larger on copper substrate than those on glass substrate, while the compressive strength is lower. The large supercooling in the product solid ification provides the condition for high nucleation rate and thus leads to nano-grained austenite and final nano-grained ferrite transformed from those small austenite grains.