Fibrication,Microstructure Characterization And Properties Of NiTi Fiber Reinforced Fe-Al Laminated Composites

In this paper,Fe-Al laminated composites and NiTi fiber reinforced Fe-Al laminated composites were prepared by vacuum hot pressing sintering furnace.According to the previous research and the preparation process of Ti/Al₃Ti,we optimized the preparation process parameters and investigated the microstructure characterization of two different materials by optical microscopy?OM?,scanning electron microscopy?SEM?,X-ray diffraction?XRD?and X-ray spectroscopy?EDS?.The result showed that the addition of NiTi fibers eliminated the original center line.But it made the microstructure even more complicated,there are many reaction layers such as Fe-Al reaction layer,eutectoid layer,intermetallic compound layer and fiber reaction layer,the main phases concludes Fe₂Al₅,Al₃Ti,Al₃Ni,NiTi and Al₃Ni₂.By investigating density of these two different materials by drainage method and comparing finds out that after added NiTi fiber,the density only increased by 2%.The mechanical properties and damping properties of two different materials were tested by means of microhardness instrument,universal testing machine and Q800DMA dynamic mechanical heat analyzer.The microhardness values of both materials show a certain periodicity.Compared to Fe-Al laminated composite,NiTi fiber reinforced Fe-Al laminated composite possesses better mechanical and damping properties.Tensile strength increased by 28.0%.The maximum compressive strength and failure strain of Fe-Al laminated composite and NiTi fiber reinforced Fe-Al laminated composite at 0.001/s strain rate are 518.83MPa,9.06%and 623.92MPa,9.18%,respectively.The maximum compressive strength of NiTi fiber reinforced Fe-Al laminated composite is 20.0%higher than the former.At 0.01/s strain rate are 539.15MPa,11.14%and 642.82MPa,8.24%,the maximum compressive strength increased by 19.2%and at 0.1/s strain rate are 551.62MPa,7.27%and 652.62MPa,8.36%.The maximum compressive strength increased by 18.3%.When the pressure direction was parallel to the fiber direction,The maximum compressive strength and failure strain under 10^-3/s strain rate of NiTi fiber reinforced Fe-Al laminated composites are 737.5 MPa and 5.41%respectively.The maximum compressive strength and failure strain under 10^-3/s strain rate of Fe-Al composites were 558.3MPa and 6.12 MPa,respectively,and the maximum compressive strength increased by 21.0%.In the three-point bending test,the maximum load of NiTi fiber reinforced Fe-Al laminated composites and Fe-Al laminated composite are 923.8N and 674.8N respectively.The damping factor had doubled.But at the same time the bending strength decreased a little.In addition,The tensile fracture of NiTi fiber reinforced Fe-Al layered composite material was analyzed,the results show that the 304-SS layers belongs to the toughness fracture,Fe-Al reaction layers shows the river pattern which belongs to cleavage fracture,NiTi fiber reaction layer is brittle fracture,contains intergranular fracture and transgranular fracture.