BAI Ya-ping,LUO Jia-jia,LI Jian-ping,YANG Zhong,GUO Yong-chun.Effect of Nano-NiAl Phase on Microstructure and Mechanical and Oxidation Properties of Fe-based Alloys[J],48(8):144-150
Effect of Nano-NiAl Phase on Microstructure and Mechanical and Oxidation Properties of Fe-based Alloys
Received:November 03, 2018  Revised:August 20, 2019
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DOI:10.16490/j.cnki.issn.1001-3660.2019.08.019
KeyWord:NiAl/Fe alloy  Nano-NiAl phase  microstructure  mechanical properties  oxidation properties
              
AuthorInstitution
BAI Ya-ping School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an , China
LUO Jia-jia School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an , China
LI Jian-ping School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an , China
YANG Zhong School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an , China
GUO Yong-chun School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an , China
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Abstract:
      The work aims to prepare the Fe-based alloy containing nano-NiAl phase with B2 structure by mechanical alloying and hot-press sintering and then study the effects of different nano-NiAl contents (30%, 40%, 50%, and 60%) on the microstructure and mechanical property of alloy. Ni powder and Al powder were used as raw materials to prepare B2 nano-NiAl powder by high-energy ball milling. The NiAl powder and Fe powder were mixed and sintered by vacuum hot-pressing sintering furnace to obtain the block sample. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to observe microstructure and analyze phases. Hardness, density, compressive strength and oxidation resistance (600 ℃) of Fe-based alloys with different contents of NiAl were tested. Hardness and compressive strength of alloy increased firstly, and then decreased with NiAl content. When NiAl content was 50wt.%, hardness and compressive strength of alloy were 35.2 HRC and 2,530 MPa respectively and the density was 6.68 g/cm3. The compressive strength of the alloy increased by 239.6% and the density decreased by 14.5% when compared with those of alloy not added with NiAl. When θ=600 ℃ and t=1200 min, the surface oxidation weight gain was reduced by 37.9% compared with that of pure iron. NiAl phase size was about 100~200 nm and the phase had the most uniform structure and the highest density. Nano-NiAl with B2 structure can effectively reduce the density of iron-based alloy and improve the mechanical properties. However, the mechanical properties of the alloy are greatly reduced, when NiAl content is too high, since nano-NiAl phase with B2 structure is a hard and brittle phase.
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