Page 57 - MSAM-3-2

Materials Science in Additive Manufacturing Heat treatment on bimetallic parts

A

B C

D E

F G

Figure 8. Microstructural analysis of interfaces. (A) Elemental mapping covering an oxide inclusion and secondary phase. Scale bars: 10 μm, magnification:
×3678; Scale bars: 2 μm, magnification: ×3678. Energy-dispersive X-ray spectroscopy (EDS) line scans for light (B) and dark (C) areas; elemental analyses
for specific spots: (D) analysis at spot D, (E) analysis at spot E; (H) EDS line scans for white band.

Table 4. Element distribution in the interface of bimetal phases, as depicted in Figure 9A. The primary phases in
17-4PH are the α-phase (martensitic and ferritic phases),
Weight % Cr Fe Ni Nb Mo Mn Si C O whereas in IN625, the dominant phase is the γ-phase
Precipitates 9.7 5.1 20.9 25.8 15.9 - 2.1 16.5 2.3 (austenitic phase). No additional phases were discovered
Oxides 39.5 - - - - 19.5 0.5 8.7 30.4 following the heat treatments, which were under 1150°C
White bands 14.8 51.9 14.6 - 1.4 - 0.3 10.6 - for various durations, with or without subsequent
17-4PH 12.6 57.6 3.1 - - 0.4 2.8 9.1 7.0 aging, of 17-4PH, with only austenite and martensite
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IN625 18.5 5.8 52.0 2.6 7.0 - 0.6 11.6 1.9 peaks detected. Both direct aging and aging following
Hot Isostatic Pressing (HIP) of 17-4PH fabricated
through PBF showed no formation of other phases. 31,47
slower cooling rate. The elongated morphology of these Furthermore, the absence of additional peaks suggests the
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carbides is due to the slow cooling rates experienced at absence of reactive phase formation within the bimetallic
the conclusion of the heat treatment process, a detail that structure of SS316L and IN718 alloy. Similarly, further
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aligns with the observed structural characteristics. XRD patterns corroborate the observation in our
The XRD patterns of phases present at the 17-4PH/ research that no new intermetallic phases form within
IN625 composite, both in as-sintered and heat-treated the diffusion zone following heat treatment, aligning
states, were analyzed to assess changes in intermetallic with the findings from EDS analyses. Independent of

Volume 3 Issue 2 (2024) 10 doi: 10.36922/msam.3281