Properties of CrMoTi Medimum-Entropy Alloy and Its In Situ Alloying Additive Manufacturing
LIU Guang1,2, CHEN Peng1,3, YAO Xiyu1, CHEN Pu1, LIU Xingchen1, LIU Chaoyang4, YAN Ming1()
1.Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China 2.School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China 3.School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, United Kingdom 4.Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China
Cite this article:
LIU Guang, CHEN Peng, YAO Xiyu, CHEN Pu, LIU Xingchen, LIU Chaoyang, YAN Ming. Properties of CrMoTi Medimum-Entropy Alloy and Its In Situ Alloying Additive Manufacturing. Acta Metall Sin, 2022, 58(8): 1055-1064.
This study verifies the body-centered cubic (bcc) formability of CrMoTi medium-entropy alloy (MEA) as a potential mold material via theoretical calculations based on the concepts of multiprincipal element alloys and practical experiments employing arc melting and additive manufacturing (AM) techniques. The hardness and thermal properties of arc-melted CrMoTi MEA were tested at room and elevated temperatures. At room temperature, the alloy possesses a hardness of 520.6 HV0.3, thermal capacity of 371 J/(kg·K), and heat conductivity of 14.0 W/(m·K). Its hardness drops to 356.0 HV0.3 at 600oC, and its thermal capacity and heat conductivity increase to 446 J/(kg·K) and 28.4 W/(m·K), respectively, at 709oC, exhibiting the characteristic of semimetals. AM techniques are efficient for fabricating highly customized molds and have been widely used. Moreover, in situ alloying can further improve the compositional flexibility in the AM process. The in situ alloying printability of two AM techniques, i.e., direct laser deposition (DLD) and selective laser melting (SLM), was investigated using a blend of elemental powders. The best densification within the AM approaches (7.46 g/cm3) is achieved using DLD, and the microhardness of DLDed samples reaches 634.6 HV0.3. Conversely, the printability of SLM is relatively restricted. The optimal density and microhardness of the SLMed sample are 7.27 g/cm3 and 605.9 HV0.3, respectively, which are lower than those of the DLDed samples. In the DLDed samples, the large melt pool can homogenize most elements but with a Cr burning loss. Mo melts insufficiently during the SLM process and remains a partially melted powder in as-built samples. Moreover, cracking is already inevitable in SLMed samples, indicating that homogenization can hardly be improved by applying excessive energy input. As a brittle bcc alloy, its matrix tends to fail under the thermal stress of the heat accumulation in the AM process. Furthermore, the phase transformation in a small melt pool also intrinsically harms printability for in situ alloying studies through AM. Results from this study reveal that DLD possesses advantages over SLM for the in situ alloying of brittle materials like CrMoTi MEA. Combining elements with adequate overlapping of the liquid zone could be essential for superior printability of AM in situ alloying, especially with a high ratio of introduced elements.
Fund: Research and Development Program Project in Key Areas of Guangdong Province(2019B010943001);Shenzhen Science and Technology Innovation Commission(JCYJ20180504165824643);Shenzhen Science and Technology Innovation Commission(JCYJ-20170817111811303)
About author: YAN Ming, professor, Tel: (0755) 88018967, E-mail: yanm@sustech.edu.cn
Table 1 Physical properties of Cr, Mo, and Ti elements[13]
Powder
Mass fraction of element / %
d / µm
C
N
O
H
Cr
0.0027
0.0912
0.0366
-
40-150
Mo
0.0027
0.0200
0.1390
-
30-100
Ti
0.0050
0.0080
0.0687
0.0031
40-150
Table 2 Chemical compositions and size (d) distributions of the elemental powders used for additive manufacturing
Fig.1 SEM-EDS image of the blended elemental powder used for direct laser deposition (DLD)
Fig.2 XRD spectrum of the blended powder used for DLD
Fig.3 XRD spectra of CrMoTi medium-entropy alloys (MEA) fabricated by arc melting, DLD, and selective laser melting (SLM) techniques
Fig.4 EBSD image of CrMoTi MEA fabricated by arc melting
Fig.5 Vickers hardnesses of CrMoTi MEA fabricated by arc melting, tested from 25oC to 600oC
Fig.6 Thermal capacity (cp ) and κ results of CrMoTi MEA tested from 28oC to 709oC (Data at 100, 300, and 500oC were obtained from regression treatment)
Fig.7 Top-views (a1, b1) and side-views (a2, b2) of CrMoTi MEA fabricated by DLD (a1, a2) and SLM (b1, b2) in situ alloying
Fig.8 Cross-section SEM image of SLMed CrMoTi MEA
Fig.9 Density-laser power (ρ-P) curve of CrMoTi MEA fabricated by DLD in situ alloying
Fig.10 Density-volumetric energy density (ρ-VED) curve of CrMoTi MEA fabricated by SLM in situ alloying
Fig.11 SEM image and corresponding EDS results of samples DLD1350W (a) and SLM167J (b) (DLD1350W denotes the DLDed sample fabricated using P = 1350 W; SLM167J denotes the SLMed sample fabricated with VED = 167 J/mm3)
Sample
Cr
Mo
Ti
Nominal
33.3
33.3
33.3
Arc melting
31.2
32.8
36.0
DLD1350W
25.5
38.6
35.9
SLM167J
36.9
23.4
39.7
Table 3 Nominal concentration of CrMoTi alloy and measured concentrations of principal elements in CrMoTi MEA fabricated by arc melting and additive manufacturing techniques
T
Hardness
κ
cp
a
oC
HV0.3
(W·m-1·K-1)
(J·kg-1·K-1)
(10-6 m2·s-1)
RT*
520.6
14.0
371
5.26
100
455.6
15.9
374
5.91
207
430.0
18.5
382
6.78
300
409.2
21.0
396
7.37
413
372.3
23.8
416
7.93
500
369.6
25.5
428
8.28
611
356.0
27.3
439
8.63
709
-
28.4
446
8.84
Table 4 Hardnesses and thermal properties of CrMoTi MEA fabricated by arc melting
Fig.12 CT results of samples DLD1350W (a) and SLM167J (b)
Fig.13 SEM image of DLDed CrMoTi MEA (a) and EDS line scanning result of the dendrite structure (b)
Fig.14 EBSD image of CrMoTi MEA fabricated by DLD (SD—scanning direction, BD—building direction along z-axis)
1
Yeh J W, Chen S K, Lin S J, et al. Nanostructured high-entropy alloys with multiple principal elements: Novel alloy design concepts and outcomes [J]. Adv. Eng. Mater., 2004, 6: 299
doi: 10.1002/adem.200300567
2
Cheng K H, Lai C H, Lin S J, et al. Recent progress in multi-element alloy and nitride coatings sputtered from high-entropy alloy targets [J]. Ann. Chim. Sci. Mat., 2006, 31: 723
doi: 10.3166/acsm.31.723-736
3
Cantor B, Chang I T H, Knight P, et al. Microstructural development in equiatomic multicomponent alloys [J]. Mater. Sci. Eng., 2004, A375-377: 213
4
Zhang Y, Zuo T T, Tang Z, et al. Microstructures and properties of high-entropy alloys [J]. Prog. Mater. Sci., 2014, 61: 1
doi: 10.1016/j.pmatsci.2013.10.001
5
Miracle D B, Senkov O N. A critical review of high entropy alloys and related concepts [J]. Acta Mater., 2017, 122: 448
doi: 10.1016/j.actamat.2016.08.081
6
DebRoy T, Wei H L, Zuback J S, et al. Additive manufacturing of metallic components—Process, structure and properties [J]. Prog. Mater. Sci., 2018, 92: 112
doi: 10.1016/j.pmatsci.2017.10.001
7
Zhang D Y, Sun S J, Qiu D, et al. Metal alloys for fusion-based additive manufacturing [J]. Adv. Eng. Mater., 2018, 20: 1700952
doi: 10.1002/adem.201700952
8
Liu G, Zhou S Y, Yang H W, et al. 3D printed CoCrFeMnNi high-entropy alloy: Microstructure and mechanical properties at room and cryogenic temperatures [J]. Mater. Rep., 2020, 34(6): 11076
Li R D, Niu P D, Yuan T C, et al. Selective laser melting of an equiatomic CoCrFeMnNi high-entropy alloy: Processability, non-equilibrium microstructure and mechanical property [J]. J. Alloys Compd., 2018, 746: 125
doi: 10.1016/j.jallcom.2018.02.298
10
Brif Y, Thomas M, Todd I. The use of high-entropy alloys in additive manufacturing [J]. Scr. Mater., 2015, 99: 93
doi: 10.1016/j.scriptamat.2014.11.037
11
Joseph J, Jarvis T, Wu X H, et al. Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted Al x CoCrFeNi high entropy alloys [J]. Mater. Sci. Eng., 2015, A633: 184
12
Popov V V, Katz-Demyanetz A, Koptyug A, et al. Selective electron beam melting of Al0.5CrMoNbTa0.5 high entropy alloys using elemental powder blend [J]. Heliyon, 2019, 5: e01188
doi: 10.1016/j.heliyon.2019.e01188
13
Guo S, Ng C, Lu J, et al. Effect of valence electron concentration on stability of fcc or bcc phase in high entropy alloys [J]. J. Appl. Phys., 2011, 109: 103505
doi: 10.1063/1.3587228
14
Yang X, Zhang Y. Prediction of high-entropy stabilized solid-solution in multi-component alloys [J]. Mater. Chem. Phys., 2012, 132: 233
doi: 10.1016/j.matchemphys.2011.11.021
15
Yao H W, Qiao J W, Gao M C, et al. MoNbTaV medium-entropy alloy [J]. Entropy, 2016, 18: 189
doi: 10.3390/e18050189
16
Takeuchi A, Inoue A. Calculations of mixing enthalpy and mismatch entropy for ternary amorphous alloys [J]. Mater. Trans., JIM, 2000, 41: 1372
doi: 10.2320/matertrans1989.41.1372
17
Takeuchi A, Inoue A. Classification of bulk metallic glasses by atomic size difference, heat of mixing and period of constituent elements and its application to characterization of the main alloying element [J]. Mater. Trans., JIM, 2005, 46: 2817
doi: 10.2320/matertrans.46.2817
18
Troparevsky M C, Morris J R, Kent P R C, et al. Criteria for predicting the formation of single-phase high-entropy alloys [J]. Phys. Rev., 2015, 5X: 011041
19
Ye Y F, Wang Q, Lu J, et al. High-entropy alloy: Challenges and prospects [J]. Mater. Today, 2016, 19: 349
doi: 10.1016/j.mattod.2015.11.026
20
Yu C F, Zhao C C, Zhang Z F, et al. Tensile properties of selective laser melted 316L stainless steel [J]. Acta Metall. Sin., 2020, 56: 683
Senkov O N, Wilks G B, Scott J M, et al. Mechanical properties of Nb25Mo25Ta25W25 and V20Nb20Mo20Ta20W20 refractory high entropy alloys [J]. Intermetallics, 2011, 19: 698
doi: 10.1016/j.intermet.2011.01.004
25
Džugan J, Halmešová K, Ackermann M, et al. Thermo-physical properties investigation in relation to deposition orientation for SLM deposited H13 steel [J]. Thermochim. Acta, 2020, 683: 178479
doi: 10.1016/j.tca.2019.178479
26
Chou H P, Chang Y S, Chen S K, et al. Microstructure, thermophysical and electrical properties in Al x CoCrFeNi (0 ≤ x ≤2) high-entropy alloys [J]. Mater. Sci. Eng., 2009, B163: 184
27
Karlsson D, Marshal A, Johansson F, et al. Elemental segregation in an AlCoCrFeNi high-entropy alloy—A comparison between selective laser melting and induction melting [J]. J. Alloys Compd., 2019, 784: 195
doi: 10.1016/j.jallcom.2018.12.267
28
Chen P, Yang C, Li S, et al. In-situ alloyed, oxide-dispersion-strengthened CoCrFeMnNi high entropy alloy fabricated via laser powder bed fusion [J]. Mater. Des., 2020, 194: 108966
doi: 10.1016/j.matdes.2020.108966
29
Tang R Z, Tian R Z. Binary Alloy Phase Digram and Crystal Structure of Intermediate Phase [M]. Changsha: Central South University Press, 2009: 399
Johnson L, Mahmoudi M, Zhang B, et al. Assessing printability maps in additive manufacturing of metal alloys [J]. Acta Mater., 2019, 176: 199
doi: 10.1016/j.actamat.2019.07.005
31
Hooper P A. Melt pool temperature and cooling rates in laser powder bed fusion [J]. Addit. Manuf., 2018, 22: 548
