scholarly journals Investigation on the Precipitates of IN718 Alloy Fabricated by Selective Laser Melting

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1128 ◽  
Author(s):  
Yu Cao ◽  
Pucun Bai ◽  
Fei Liu ◽  
Xiaohu Hou

The microstructure and precipitates of INCONEL 718 alloy (IN718) fabricated by selective laser melting (SLM) are investigated. The matrix is comprised of the elongated γ grains along Z direction, tilting a few degrees. The microstructure mainly consists of a cellular–columnar structure with fine first dendrite arm space of 1–1.5 µm originated from the rapid solidification rate locally. The precipitates of the SLMed IN718 are confirmed to be a significant amount of Laves in the form of irregular bulk distribution, small amount of carbonitride and spherical Al2O3 particles in nanoscale. Some of the carbonitrides grow separately and some of the carbonitrides enwrap the Al2O3 fully or partly, forming the shell structure of the Al2O3–carbonitride. The reheating effect from the following layers to the previous layers have not reached the solid-state transformation temperature of the γ′ and γ″.

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1001
Author(s):  
Zongxian Song ◽  
Wenbin Gao ◽  
Dongpo Wang ◽  
Zhisheng Wu ◽  
Meifang Yan ◽  
...  

This study investigates the very-high-cycle fatigue (VHCF) behavior at elevated temperature (650 °C) of the Inconel 718 alloy fabricated by selective laser melting (SLM). The results are compared with those of the wrought alloy. Large columnar grain with a cellular structure in the grain interior and Laves/δ phases precipitated along the grain boundaries were exhibited in the SLM alloy, while fine equiaxed grains were present in the wrought alloy. The elevated temperature had a minor effect on the fatigue resistance in the regime below 108 cycles for the SLM alloy but significantly reduced the fatigue strength in the VHCF regime above 108 cycles. Both the SLM and wrought specimens exhibited similar fatigue resistance in the fatigue life regime of fewer than 107–108 cycles at elevated temperature, and the surface initiation mechanism was dominant in both alloys. In a VHCF regime above 107–108 cycles at elevated temperature, the wrought material exhibited slightly better fatigue resistance than the SLM alloy. All fatigue cracks are initiated from the internal defects or the microstructure discontinuities. The precipitation of Laves and δ phases is examined after fatigue tests at high temperatures, and the effect of microstructure on the formation and the propagation of the microstructural small cracks is also discussed.


2009 ◽  
Vol 38 (11) ◽  
pp. 1080-1081 ◽  
Author(s):  
Hironori Saito ◽  
Mitsuaki Suzuki ◽  
Hiroshi Miyamae ◽  
Naoto Hayashi ◽  
Keiji Kobayashi

2015 ◽  
Vol 120 (3) ◽  
pp. 570-587 ◽  
Author(s):  
Steven J. Jaret ◽  
William R. Woerner ◽  
Brian L. Phillips ◽  
Lars Ehm ◽  
Hanna Nekvasil ◽  
...  

1990 ◽  
Vol 205 ◽  
Author(s):  
Gillian E. Winters ◽  
K.M. Unruh ◽  
C.P. Swann ◽  
M.E. Patt ◽  
B.E. White ◽  
...  

AbstractMultilayer films, consisting of alternating layers of crystalline Ni and Ti, have been prepared by RF sputter deposition over a range of modulation wavelengths corresponding to an overall composition of Ni50Ti50. These films have been characterized by xray diffraction and Rutherford backscattering measurements. The solid-state transformation by interdiffusional mixing of the individual layers has been directly studied by differential scanning calorimetry and correlated with structural measurements. These measurements indicate that the solid-state reaction of Ni and Ti multilayers proceeds through the formation of a metastable solid solution of Ti in Ni followed by the formation of intermetallic equilibrium compounds. No direct calorimetric or structural evidence for the formation of an amorphous Ni-Ti phase has been found in these samples.


2021 ◽  
pp. 159992
Author(s):  
Germán Pérez-Zúñiga ◽  
Gabriel Herrera-Pérez ◽  
Ysmael Verde-Gómez ◽  
Ana María Valenzuela-Muñiz

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