Sn was used to replace Al in Co38Ni34Al28 alloy. The microstructure and microhardness of Co38Ni34Al28-xSnx （x=0, 1, 2, 3） magnetic shape memory alloys were investigated at different heat treatment temperatures （137...Sn was used to replace Al in Co38Ni34Al28 alloy. The microstructure and microhardness of Co38Ni34Al28-xSnx （x=0, 1, 2, 3） magnetic shape memory alloys were investigated at different heat treatment temperatures （1373 K, 1473 K, and 1573 K） for 2 h. The results show that more Sn substitution reduces the content of γ-phase and a partial phase of martensite can be obtained in Co38Ni34Al28-xSnx （x=1, 2, 3） alloys after treatment at 1573 K for 2 h. The maximum martensite phase appears when 2% Al is substituted by Sn. The reverse martensitic transformation temperature of Co38Ni34Al28-xSnx alloys increases at x=1 and 2, then decreases as x=3. As the content of Sn and the temperature increase, the microhardness will increase.展开更多
The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are compos...The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are composed of the single FCC phase.The BCC and B2 phases are found.It is confirmed that the BCC phase in the Al7Cr20Fe66Ni7 alloy is transformed from the FCC phase at about 900℃ during cooling.While in the 800℃-annealed Al7Cr20Fe60Ni13 alloy,the FCC phase is stable and the hardness decreases.After annealing at 1000℃,for the precipitation of the B2 particles,the Al content in the FCC phase decreases,which results in decreasing of the alloy hardness.Moreover,after annealing at 800℃,a small amount of Al-rich B2 particles precipitate at the phase boundary and some nanocrystal BCC phase precipitates in the FCC matrix,which increases the hardness of the Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=41−49)alloys.These results will help to the composition design and processing design of the Al−Cr−Fe−Ni based high-entropy alloys.展开更多
The morphology evolution and phase transformation of Al9(Mn,Ni)2 eutectic phase in an Al-4Ni-2Mn alloy during heat treatment at 600°C were studied by scanning electron microscopy(SEM)and transmission electron mic...The morphology evolution and phase transformation of Al9(Mn,Ni)2 eutectic phase in an Al-4Ni-2Mn alloy during heat treatment at 600°C were studied by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Results show that nearly all of the eutectic fibers change into prolate ellipsoid and spherical particles in the process of heat treatment,and Ostwald ripening phenomenon occurs in the eutectic region with the increase of the heat treatment time.Besides,a phase transformation from Al9(Mn,Ni)2 to O-phase is confirmed.The morphologies of the transformed particles indicate that the O-phase preferentially nucleates on the specific crystal plane of the Al9(Mn,Ni)2 eutectic phase and grows in a certain direction.During the phase transformation,the(010)[001]slip system in O-phase is activated,and the resultant slip traces appear on the surface of some O-phase particles.展开更多
基金Projects (50771037, 50371020) supported by the National Natural Science Foundation of ChinaProject (2011B090400485) supported by the Combination Project for Guangdong Province and the Ministry of Education, China
文摘Sn was used to replace Al in Co38Ni34Al28 alloy. The microstructure and microhardness of Co38Ni34Al28-xSnx （x=0, 1, 2, 3） magnetic shape memory alloys were investigated at different heat treatment temperatures （1373 K, 1473 K, and 1573 K） for 2 h. The results show that more Sn substitution reduces the content of γ-phase and a partial phase of martensite can be obtained in Co38Ni34Al28-xSnx （x=1, 2, 3） alloys after treatment at 1573 K for 2 h. The maximum martensite phase appears when 2% Al is substituted by Sn. The reverse martensitic transformation temperature of Co38Ni34Al28-xSnx alloys increases at x=1 and 2, then decreases as x=3. As the content of Sn and the temperature increase, the microhardness will increase.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51771035,51671037)Natural Science Foundation of Jiangsu Province,China(BK20161190)the Priority Academic Program of Jiangsu Higher Education Institutions,China.
文摘The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are composed of the single FCC phase.The BCC and B2 phases are found.It is confirmed that the BCC phase in the Al7Cr20Fe66Ni7 alloy is transformed from the FCC phase at about 900℃ during cooling.While in the 800℃-annealed Al7Cr20Fe60Ni13 alloy,the FCC phase is stable and the hardness decreases.After annealing at 1000℃,for the precipitation of the B2 particles,the Al content in the FCC phase decreases,which results in decreasing of the alloy hardness.Moreover,after annealing at 800℃,a small amount of Al-rich B2 particles precipitate at the phase boundary and some nanocrystal BCC phase precipitates in the FCC matrix,which increases the hardness of the Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=41−49)alloys.These results will help to the composition design and processing design of the Al−Cr−Fe−Ni based high-entropy alloys.
文摘The morphology evolution and phase transformation of Al9(Mn,Ni)2 eutectic phase in an Al-4Ni-2Mn alloy during heat treatment at 600°C were studied by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Results show that nearly all of the eutectic fibers change into prolate ellipsoid and spherical particles in the process of heat treatment,and Ostwald ripening phenomenon occurs in the eutectic region with the increase of the heat treatment time.Besides,a phase transformation from Al9(Mn,Ni)2 to O-phase is confirmed.The morphologies of the transformed particles indicate that the O-phase preferentially nucleates on the specific crystal plane of the Al9(Mn,Ni)2 eutectic phase and grows in a certain direction.During the phase transformation,the(010)[001]slip system in O-phase is activated,and the resultant slip traces appear on the surface of some O-phase particles.
