Development of Diffraction Research Methodologies for Mediloy S-CO Alloy Speciments Made Using LPBF Additive Manufacturing

Elżbieta Gadalińska; Maciej Malicki; Anna Trykowska; Grzegorz Moneta

doi:10.2478/fas-2023-0006

Figures & Tables

The printed specimens of all 3 directions and all 5 printing sets. The specimens printed in the direction parallel to their axis (row a), inclined 45° to their axis (row b), and perpendicular to their axis (row c).

Temperature change during heat treatment.

Effect of specimen etching with: a) H2O2 solution in hydrochloric acid, (etchant no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30%)), b) H2O2 solution in hydrochloric acid (ref. no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30 %)) – electrolytic etching at 4V,
c) 10% aqueous solution of oxalic acid – electrolytic etching at 6 V,
d) 38% aqueous solution of hydrochloric acid – 3h etching,
e) and f) 60 ml HNO3+ 40 ml H2O solution (ref. no. 219 according to Kundra, 2023) – electrolytic etching at 1 V – polarized light image,
g) Nital 2% (etchant no. 74 according to Kundra, 2023) – electrolytic etching at 8 V, h) solution of 6.5 ml HCl + 1.5 ml HNO3 + 1.8 g CH3COOH + 1.17 ml H2O. — Effect of specimen etching with: a) H2O2 solution in hydrochloric acid, (etchant no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30%)), b) H2O2 solution in hydrochloric acid (ref. no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30 %)) – electrolytic etching at 4V, c) 10% aqueous solution of oxalic acid – electrolytic etching at 6 V, d) 38% aqueous solution of hydrochloric acid – 3h etching, e) and f) 60 ml HNO3+ 40 ml H2O solution (ref. no. 219 according to Kundra, 2023) – electrolytic etching at 1 V – polarized light image, g) Nital 2% (etchant no. 74 according to Kundra, 2023) – electrolytic etching at 8 V, h) solution of 6.5 ml HCl + 1.5 ml HNO3 + 1.8 g CH3COOH + 1.17 ml H2O.

X-ray diffractogram obtained for the specimen before heat treatment with the Braggs reflections indexed.

Microstructure of specimen no. 1 (a, b), no. 2 (c, d), no. 3 (e, f), no. 4 (g, h), no. 5 (i, j).

X-ray diffractogram obtained for the specimen after heat treatment with the Braggs reflections indexed: the yellow square corresponds to reflections of the cubic Co3O4 phase and the green stars to reflections of the hexagonal Cr0.8Co0.2 phase.

Results of stress measurements in the circumferential direction before heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

Results of stress measurements in the axial direction before heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

Results of stress measurements in the circumferential direction after heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

Results of stress measurements in the axial direction after heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

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etching method	observations	see Fig. 3
H₂O₂ solution in hydrochloric acid (etchant no. 22 according to Bhavar et al. (2017): 100 ml HCl + 0.5 ml H₂O₂ (30%)).	Promising results: the ability to distinguish grains based on the shade of their colors. Intense etching of melt boundaries and lack of etching of grain boundaries prevents their precise determination.	a
H₂O₂ solution in hydrochloric acid (ref. no. 22 according to Bhavar et al. (2017): 100 ml HCl + 0.5 ml H₂O₂ (30 %)) – electrolytic at 4 V.	Intensive etching of melt boundaries, grain boundaries invisible.	b
Kalling’s etchant 1 and 2.	Etching effects were not obtained.	-
10% aqueous solution of oxalic acid – electrolytic etching at 6 V	Etching of melt boundaries, grain boundaries invisible.	c
38% aqueous solution of hydrochloric acid.	A 10-minute etching first extracted the boundaries of the melts. A 3-hour etching revealed grains, but there is difficulty in precisely defining their boundaries.	d
60 ml HNO₃ + 40 ml H₂O solution (ref. no. 219 according to Bhavar et al., 2017) – electrolytic etching at 1 V.	Promising results for observations with polarized light (the ability to distinguish grains based on the shade of their colors). Intense etching of melt boundaries and lack of etching of grain boundaries prevents their precise determination.	e, f
Berach’s etchant III with the addition of sodium pyrosulfate (1 g per 100 ml).	No apparent etching effects were obtained.
Nital 2% (etchant no. 74 according to Kundra, 2023) – electrolytic etching at 8 V.	Etched melt boundaries in the first place, no etching of grain boundaries. Inability to distinguish between grains.	g
solution of 6.5 ml HCl + 1.5 ml HNO₃ + 1.8 g CH₃COOH + 1.17 ml H₂O.	Promising results for observations with polarized light (the ability to distinguish grains based on the shade of their colors). Intense etching of melt boundaries and lack of etching of grain boundaries prevents their precise determination.	h

Chemical composition of Mediloy S-Co alloy_

Co	Cr	Mo	W	Si
63.9 %	24.7 %	5 %	5.4 %	<1 %

Printing parameters, energy densities and porosities for all parameter sets_

Printing parameters set no.	Laser power [W]	Scanning speed [mm/s]	Single layer thickness [mm]	Hatch spacing [mm]	Energy density [J/mm³]	Porosity [%]
1	optimized parameter set				119.8	0.05%
2	95	1000	0.35	0.09	30.2	8.06%
3	120	1200	0.03	0.075	44.4	1.60%
4	70	1200	0.02	0.105	27.8	16.81%
5	145	800	0.02	0.06	151.0	Ref.

Phase analysis results for the specimen after heat treatment_

phase	ICDD card no.	structure space group	lattice parameters [Å]	%
Cr_0.8Co_0.2	01-071-7109	hexagonalP63/mmc194	a₀ = b₀ = 2.52c₀= 4.062	44.5
W_0.04Co_0.96	04-003-2727	hexagonalP63/mmc194	a₀ = b₀= 2.523c₀ = 4.083	16.4
W_0.12Co_0.88	04-003-2728	cubic FCCFm-3m225	a₀ = 3.586	6.8
Co₃0₄	04-014-7747	cubicFd-3m227	a₀ = 8.1773	32.3

Phase analysis results for the specimen before heat treatment_

phase	ICDD card no.	structure space group	lattice parameters [Å]	%
W_0.12Co_0.88	04-003-2728	cubic FCCFm-3m225	a₀ = 3.586	73.7
Cr_0.38Co_0.62	04-002-1030	hexagonalP63/mmc194	a₀ = b₀ = 2.53c₀ = 4.08	12.4
Co	04-006-8066	hexagonalP63/mmc194	a₀ = b₀ = 2.052c₀ = 4.09	11.4
Mo Co₃	04-004-3529	hexagonalP63/mmc194	a₀ = b₀ = 5.1245c₀ = 4.1125	2.5

Development of Diffraction Research Methodologies for Mediloy S-CO Alloy Speciments Made Using LPBF Additive Manufacturing

Figures & Tables

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Chemical composition of Mediloy S-Co alloy_

Printing parameters, energy densities and porosities for all parameter sets_

Phase analysis results for the specimen after heat treatment_

Phase analysis results for the specimen before heat treatment_

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