Composition, Microstructure, Phase Constitution and Fundamental Physicochemical Properties of Low-Melting-Point Multi-Component Eutectic Alloys

Abstract

Abstract:

Low-melting-point alloys have an extensive applications in the fields of materials processing, phase change energy storage, electronic and electrical automatic control, continuous casting simulation, welding, etc. Specifically, the eutectic compositions make up a large number of low-melting-point alloys that are exploited because of their desirable features like single melting peaks, excellent operational reliability, and casting fluidity. However, the fundamental physicochemical properties from the current available literature on low-melting-point multi-component eutectic alloys (LMP-MCEAs) are rather rare and lowly accurate, including the exact melting temperatures and compositions, constituent phases, microstructures and morphologies, melting enthalpies, specific heats, densities, and so on. This lack of information seriously limits the development and application of low-melting-point multi-component eutectic alloys. In this paper, the low-melting-point multi-component eutectic alloys composed of Bi, Cd, Sn, Pb, and In elements synthesized by high vacuum induction melting and fundamental data were investigated by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and density analysis instrument. Most of the LMP-MCEAs with complex eutectic morphology structures and XRD diffraction patterns could be explained with the fact that they were three-phase eutectic alloys with mixed growth way. Generally, LMP-MCEAs present an extremely low melting point between 48.3 and 124 °C and high density between 8 and 10 g/cm3.

Key words: Multicomponent alloys, Eutectic alloy, Microstructure, Physicochemical properties

Zhou Kaiyao,Tang Zhongyi,Lu Yiping,Wang Tongmin,Wang Haipeng,Li Tingju. Composition, Microstructure, Phase Constitution and Fundamental Physicochemical Properties of Low-Melting-Point Multi-Component Eutectic Alloys[J]. J. Mater. Sci. Technol., 2017, 33(2): 131-154.

Figures/Tables 50

Table 1 Nominal eutectic compositions of LMP-MCEAs and previous scientific achievements of ternary and multi-component alloys[1]; [2]; [3]; [4]; [12]; [13]; [14] ; [15]

Alloy	Alloy composition (wt%)					Published melting temperature (°C)	Phase constitution	Microstructure	Density (g/cm³)	E (GPa)
Alloy	In	Sn	Bi	Cd	Pb	Published melting temperature (°C)	Phase constitution	Microstructure	Density (g/cm³)	E (GPa)
1	25.20	17.30	57.50			78.80	-	-	-	-
2	51.34	15.56	33.10			-	-	-	-	-
3	4.00	40.00	56.00			130.00	-	-	-	-
4		22.00	50.00		28.00	100.00	-	-	-	12.12 ± 1.16
5		15.50	52.50		32.00	96.00	-	-	-	-
6		16.00	52.00		32.00	95.00	Bi₃Pb₇,Bi-Sn intermetallic compounds, Bi and Sn body-centered tetragonal phase	-	-	-
7		26.00	53.00	21.00		102.50	faceted(Bi)- faceted(Cd)- non-faceted (βCd-Sn)type	-	-	-
8			51.60	8.20	40.20	91.50	-	-	-	-
9		51.20		30.60	18.20	143.00	-	-	-	-
10	10.50	19.00	53.50		17.00	60.00	-	-	-	-
11	21.00	12.00	49.00		18.00	58.00	-	-	-	-
12		13.30	50.00	10.00	26.70	70.00	-	-	-	-
13	19.10	8.30	44.70	5.30	22.60	46.70	-	-	-	-

Table 2 Physical parameters of elements

Parameters	In	Sn	Bi	Cd	Pb
Electronegativity	1.78	1.96	2.02	1.69	2.33
Valence electron concentration	3	4	5	12	4
Atomic radius (pm)	155	145	160	155	180
Melting point (°C)	156.6	231.93	271.3	321.07	327.46

Table 3 Chemical mixing enthalpies (ΔHmix) of the atomic pairs among the alloying elements (kJ/mol)[16]

	In	Sn	Bi	Cd	Pb
In	-	0	-1	0	-1
Sn		-	1	0	2
Bi			-	1	0
Cd				-	2
Pb					-

Table 4 Microstructure morphologies, melting points, latent heats of phase change and phase compositions of thirteen low melting point eutectic alloys

Alloy composition (wt%)	Melting point (°C)	Latent heat of phase change (J/g)	Latent heat of phase change (J/cm³)	Density (g/cm³)	Microstructure	Phases	Type
In_25.2Sn_17.3Bi_57.5	80.70	32.47	282.359	8.696	Complex lamellar eutectic structure	Sn solid solution, Bi, BiIn	Eutectic
In_51.34Sn1_5.56Bi_33.1	60.42	24.34	195.986	8.052	Quasi-regular structure	Sn solid solution, BiIn₂	Eutectic
In₄Sn₄₀Bi₅₆	101.13	3.87	32.911	8.525	Complex-regular structure	Sn solid solution, Bi solid solution	Near-eutectic
Sn₂₂Bi₅₀Pb₂₈	97.06	17.55	165.619	9.437	Complex lamellar structure	Sn solid solution, Bi solid solution, Pb₇Bi₃	Near-eutectic
Sn_15.5Bi_52.5Pb₃₂	96.84	21.64	210.211	9.714	Complex-regular structure	Sn solid solution, Bi solid solution, Pb₇Bi₃	Near-eutectic
Sn₁₆Bi₅₂Pb₃₂	96.91	22.02	210.643	9.566	Quasi-regular structure	Sn solid solution, Bi solid solution, Pb₇Bi₃	Near-eutectic
Sn₂₆Bi₅₃Cd₂₁	92.55	2.52	22.108	8.773	Complex-regular structure	Sn solid solution, Bi solid solution, Cd solid solution	Near-eutectic
Bi_51.6Cd_8.2Pb_40.2	92.97	26.66	277.717	10.417	Broken lamellar structure	Bi solid solution, Cd solid solution, Pb₇Bi₃	Eutectic
Sn_51.2Cd_30.6Pb_18.2	144.99	40.6	329.672	8.120	Complex-regular structure	Sn solid solution, Pb solid solution, Cd solid solution	Near-eutectic
In_10.5Sn₁₉Bi_53.5Pb₁₇	60.66-76.18	16.91	154.879	9.159	Complex-regular structure	Bi solid solution, Sn solid solution, BiIn, PbBi	Not eutectic
In₂₁Sn₁₂Bi₄₉Pb₁₈	59.73	27.07	249.829	9.229	Complex-regular structure	Sn solid solution, PbBi, InBi	Eutectic
Sn_13.3Bi₅₀Cd₁₀Pb_26.7	72.14	30.35	290.814	9.582	Complex-regular structure	Sn solid solution, Bi solid solution, Cd	Eutectic
In_19.1Sn_8.3Bi_44.7Cd_5.3Pb_22.6	48.30	28.53	266.185	9.330	Complex-regular structure	Sn solid solution, Bi solid solution, InBi	Eutectic

Table 4 Microstructure morphologies, melting points, latent heats of phase change and phase compositions of thirteen low melting point eutectic alloys

Alloy composition (wt%)	Melting point (°C)	Latent heat of phase change (J/g)	Latent heat of phase change (J/cm³)	Density (g/cm³)	Microstructure	Phases	Type
In_25.2Sn_17.3Bi_57.5	80.70	32.47	282.359	8.696	Complex lamellar eutectic structure	Sn solid solution, Bi, BiIn	Eutectic
In_51.34Sn1_5.56Bi_33.1	60.42	24.34	195.986	8.052	Quasi-regular structure	Sn solid solution, BiIn₂	Eutectic
In₄Sn₄₀Bi₅₆	101.13	3.87	32.911	8.525	Complex-regular structure	Sn solid solution, Bi solid solution	Near-eutectic
Sn₂₂Bi₅₀Pb₂₈	97.06	17.55	165.619	9.437	Complex lamellar structure	Sn solid solution, Bi solid solution, Pb₇Bi₃	Near-eutectic
Sn_15.5Bi_52.5Pb₃₂	96.84	21.64	210.211	9.714	Complex-regular structure	Sn solid solution, Bi solid solution, Pb₇Bi₃	Near-eutectic
Sn₁₆Bi₅₂Pb₃₂	96.91	22.02	210.643	9.566	Quasi-regular structure	Sn solid solution, Bi solid solution, Pb₇Bi₃	Near-eutectic
Sn₂₆Bi₅₃Cd₂₁	92.55	2.52	22.108	8.773	Complex-regular structure	Sn solid solution, Bi solid solution, Cd solid solution	Near-eutectic
Bi_51.6Cd_8.2Pb_40.2	92.97	26.66	277.717	10.417	Broken lamellar structure	Bi solid solution, Cd solid solution, Pb₇Bi₃	Eutectic
Sn_51.2Cd_30.6Pb_18.2	144.99	40.6	329.672	8.120	Complex-regular structure	Sn solid solution, Pb solid solution, Cd solid solution	Near-eutectic
In_10.5Sn₁₉Bi_53.5Pb₁₇	60.66-76.18	16.91	154.879	9.159	Complex-regular structure	Bi solid solution, Sn solid solution, BiIn, PbBi	Not eutectic
In₂₁Sn₁₂Bi₄₉Pb₁₈	59.73	27.07	249.829	9.229	Complex-regular structure	Sn solid solution, PbBi, InBi	Eutectic
Sn_13.3Bi₅₀Cd₁₀Pb_26.7	72.14	30.35	290.814	9.582	Complex-regular structure	Sn solid solution, Bi solid solution, Cd	Eutectic
In_19.1Sn_8.3Bi_44.7Cd_5.3Pb_22.6	48.30	28.53	266.185	9.330	Complex-regular structure	Sn solid solution, Bi solid solution, InBi	Eutectic

Fig.1 High-purity silica crucible had an inner diameter of Φ14.72 mm and a length of 70.90 mm

Fig.2 (a) SEM backscattered electron image of In25.2Sn17.3Bi57.5 alloy; (b-d) enlarged scales of (a); (e-g) elemental mappings of Bi, Sn, and In of (d)

Fig.3 Composition analysis of different regions by EDS

Fig.4 DSC trace of In25.2Sn17.3Bi57.5 alloy

Fig.5 XRD pattern of In25.2Sn17.3Bi57.5 alloy

Fig.6 (a) SEM backscattered electron image of In51.34Sn15.56Bi33.1 alloy; (b, c) enlarged scale of (a); (d-f) elemental mappings of Bi, Sn, and In of (c)

Fig.7 DSC trace of In51.34Sn15.56Bi33.1 alloy

Fig.8 XRD pattern of In51.34Sn15.56Bi33.1 alloy

Fig.9 (a) SEM backscattered electron image of In4Sn40Bi56 alloy; (b, c) enlarged scale of (a)

Fig.10 (a) SEM backscattered electron image of In4Sn40Bi56 alloy; (b-d) elemental mappings of Sn, In, and Bi of (a)

Fig.11 DSC trace of In4Sn40Bi56 alloy

Fig.12 XRD pattern of In4Sn40Bi56 alloy

Fig.13 (a) SEM backscattered electron image of Sn22Bi50Pb28 alloy; (b) enlarged scale of (a); (c, d) enlarged scale of different regions in (b); (e-j) elemental mappings of Bi, Pb, and Sn

Fig.14 DSC trace of Sn22Bi50Pb28 alloy

Fig.15 XRD pattern of Sn22Bi50Pb28 alloy

Fig.16 (a) SEM backscattered electron image of Sn15.5Bi52.5Pb32 alloy; (b, c) enlarged scale of different regions in (a); (d-f) elemental mappings of Bi, Pb, and Sn of (c)

Fig.17 DSC trace of Sn15.5Bi52.5Pb32 alloy

Fig.18 XRD pattern of Sn15.5Bi52.5Pb32 alloy

Fig.19 (a) SEM backscattered electron image of Sn16Bi52Pb32 alloy; (b, c) enlarged scale of (a); (d-f) elemental mappings of Bi, Pb and Sn of (c)

Fig.20 Composition analysis of different regions by EDS

Fig.21 DSC trace of Sn16Bi52Pb32 alloy

Fig.22 XRD pattern of Sn16Bi52Pb32 alloy

Fig.23 (a) SEM backscattered electron image of Sn26Bi53Cd21 alloy; (b, c) enlarged scale of (a); (d-f) elemental mappings of Bi, Cd and Sn of (c)

Fig.24 Composition analysis of different regions by EDS

Fig.25 DSC trace of Sn26Bi53Cd21 alloy

Fig.26 XRD pattern of Sn26Bi53Cd21 alloy

Fig.27 (a) SEM backscattered electron image of Bi51.6Cd8.2Pb40.2 alloy; (b, c) enlarged scale of (a); (d-f) elemental mappings of Bi, Cd and Pb of (c)

Fig.28 DSC trace of Bi51.6Cd8.2Pb40.2 alloy

Fig.29 XRD pattern of Bi51.6Cd8.2Pb40.2 alloy

Fig.30 (a) SEM backscattered electron image of Sn51.2Cd30.6Pb18.2 alloy; (b, c) enlarged scale of (a); (d-f) elemental mappings of Cd, Pb and Sn of (c)

Fig.31 DSC trace of Sn51.2Cd30.6Pb18.2 alloy

Fig.32 XRD pattern of Sn51.2Cd30.6Pb18.2 alloy

Fig.33 (a) SEM backscattered electron image of In10.5Sn 19Bi53.5Pb17 alloy; (b-d) enlarged scale of (a); (e-h) elemental mappings of Bi, In, Pb and Sn of (d)

Fig.34 Results of composition analysis of different regions by EDS

Fig.35 DSC trace of In10.5Sn 19Bi53.5Pb17 alloy

Fig.36 XRD pattern of In10.5Sn 19Bi53.5Pb17 alloy

Fig.37 (a) SEM backscattered electron image of In21Sn12Bi49Pb18 alloy; (b) enlarged scale of (a); (c-f) elemental mappings of Bi, In, Pb and Sn of (b)

Fig.38 Results of composition analysis of different regions by EDS

Fig.39 DSC trace of In21Sn12Bi49Pb18 alloy

Fig.40 XRD pattern of In21Sn12Bi49Pb18 alloy

Fig.41 (a) SEM backscattered electron image of Sn13.3Bi50Cd10Pb26.7 alloy; (b) enlarged scale of (a); (c-f) elemental mappings of Bi, Pb, Sn, and Cd of (b)

Fig.42 DSC trace of Sn13.3Bi50Cd10Pb26.7 alloy

Fig.43 XRD pattern of Sn13.3Bi50Cd10Pb26.7 alloy

Fig.44 (a) SEM backscattered electron image of In19.1Sn 8.3Bi44.7Cd5.3Pb22.6 alloy; (b) enlarged scale of (a); (c-g) elemental mappings of Bi, Cd, In, Pb, and Sn of (b)

Fig.45 (DSC trace of In19.1Sn 8.3Bi44.7Cd5.3Pb22.6 alloy

Fig.46 XRD pattern of In19.1Sn 8.3Bi44.7Cd5.3Pb22.6 eutectic alloy

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