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Effect of La2O3 on microstructure and properties of Cu20Fe80 alloy by microwave sintering

This content has been downloaded from IOPscience. Please scroll down to see the full text. 2017 IOP Conf. Ser.: Mater. Sci. Eng. 207 012014 (http://iopscience.iop.org/1757-899X/207/1/012014) View the table of contents for this issue, or go to the journal homepage for more Download details: IP Address: 154.16.44.248 This content was downloaded on 17/06/2017 at 03:56 Please note that terms and conditions apply.

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ACMME 2017 IOP Publishing IOP Conf. Series: Materials Science and Engineering 207 (2017) 012014 doi:10.1088/1757-899X/207/1/012014 1234567890

Effect of La2O3 on microstructure and properties of Cu20Fe80 alloy by microwave sintering Junwei Fu1, Suhua Yin1, Zhongqi Dong1,*, Yang Wang2, Yanxia Liu1 1

Engineering Research Institute, Hebei College of Industry and Technology, Shijiazhuang 050091, China 2 School of Materials Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei, China 050000, China *Corresponding author e-mail: [email protected] Abstract. It was prepared that Cu20Fe80 alloys using the mechanical alloying and cold pressing and the microwave sintering. The microstructure and the phase composition of Cu20Fe80 alloy were analyzed by SEM and XRD, respectively. The density and hardness of the alloys were measured. The effect of La2O3 on microstructure and properties of Cu20Fe80 alloy was investigated during the microwave sintering. The results have shown that the powder milling structure of Cu20Fe80 alloy is a flake layer which is refined and the mechanical alloying enhanced with increasing La2O3 content; The microstructure of the Cu20Fe80 alloy powder blank cold pressed is lamellar which gradually become dense, the density increases and the formability is improved with the increase of La2O3 content; The microstructure of the Cu20Fe80 alloys sintering was lamellar that the voids and the density and the hardness change with the increase of La2O3 content and the best La2O3 content was 0.2%.

1. Introduction Iron - Copper - based powder metallurgy bearing material, which can save non-ferrous metals and reduce the cost of raw materials [1-3]. But the traditional bearing mixed iron copper powder, the compressive strength, hardness is based on copper based materials on the increased slightly, poor corrosion resistance, and will inevitably generate and microstructure segregation caused by inhomogeneity of hard phase and the performance of the resulting running noise increases and shorten the service life of the bearing, the in the large-scale automation production process, is not conducive to ensure the consistency and stability of the product performance[4-7]. In this paper, La2O3 was added in the preparation of Cu-Fe alloy, and the effect of La2O3 on the microstructure and properties of Cu-Fe alloy during mechanical alloying and cold pressing microwave sintering was studied. 2. Experimental Methods The purity of raw materials (Cu alloy particle size 3~5 m Fe (tested), mesh size -200) and La2O3 99.99% (atomic ratio), according to the chemical composition of Cu20Fe80 alloy configuration, the sample weight is about 5-10 grams. The raw material powder was put into QM-1SP type planetary high energy ball mill and was protected by anhydrous ethanol. The alloy was grinded by 6h in high energy ball mill. Cu20Fe80 alloy is placed in a vacuum drying oven after grinding, vacuum to 2 * 10-2Pa,

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1

ACMME 2017 IOP Publishing IOP Conf. Series: Materials Science and Engineering 207 (2017) 012014 doi:10.1088/1757-899X/207/1/012014 1234567890

temperature 318K, drying 2~3h. After drying, the particle size of Cu20Fe80 alloy powder was determined by BT-9300S laser particle size distribution instrument. DNS100 electronic universal testing machine was used to make cold pressing of Cu20Fe80 alloy powder in 200Mpa. The cold pressing sintering under control Cu20Fe80sample loading platform of the central vacuum microwave MKX-T3-1 sintering machine, sintering time 20min, temperature from room temperature to 950 degrees C, sintering by use of two-color infrared thermometer MRISBSF alloy temperature monitoring. Comes with VEGA3SBH scanning electron microscope and scanning electron microscope energy spectrum analysis and phase composition of alloy microstructure. X ray diffraction determination of powder samples by Cu-K target in X - ray diffraction spectrum, crystal structure analysis of samples. 3. Experimental results and discussion 3.1. Mechanical alloying Cu20Fe80 powder microstructure analysis Figure 1 (a), (b) and (c) were Cu, Fe and La2O3 powder morphology, Cu, Fe and La2O3 were small and multi grain, Fe particles larger. Figure 2 (a) ~ (d) for the morphology of Cu20Fe80 mechanical alloying 6h, and milling powder, changed CuFe powder, Cu20Fe80 powder after the mechanical alloying are mostly lamellar particles of lamellar particles and fine fraction (Figure 3), and the surface layer flake particles have the fracture shape, the edge is sharp teeth marks in the shape of powder surface with small particles. It can be seen from the figure of powder grinding 6h containing 0.6% La2O3, the size ratio between the 6.5~130 selection m was higher than that of the content of 0 and 0.2%, the vast majority of powder refinement to about 35 m selection. The mechanical alloying of Cu20Fe80 powder was analyzed by means of component surface scan (Figure 2d). It was found that the powder was rich in Cu and rich in Fe, and the rich Fe layer was larger than that of the rich Cu layer. Figure 4 is the X ray diffraction Cu20Fe80 powder containing 0~1.0% La2O3 mechanical alloying of 6h spectrum, Cu, Fe diffraction peaks do not overlap, but increased the content of La2O3 Cu peaks with the diffraction peak first increased and then decreased, with the increase of Fe peak La2O3 content with the first decreased and then increased, in La2O3 content of 0.2% for the transition point, showed that the La2O3 content in formation forced solid solution of Fe and Cu, have enhanced first and then weakened.

Fig.1 The morphology of powder of (a) Cu and (b) Fe (c) La2O3

Fig.2 The morphology of Cu20Fe80 powders by mechanical alloying (a) 0.0% (b) 0.2% (c) 0.8% SEM and (b) Surface scan

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ACMME 2017 IOP Publishing IOP Conf. Series: Materials Science and Engineering 207 (2017) 012014 doi:10.1088/1757-899X/207/1/012014 1234567890

10 100

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Fig.3 Particle size distribution of Cu20Fe80 Fig.4 XRD patterns of powders Cu20Fe80 Powders by mechanical alloying powders by mechanical alloying 3.2. Microstructure analysis of Cu20Fe80 alloy powder by cold pressing mechanical alloying

Fig.5 The fracture morphology of Cu60Cr40 cold pressed green (a) 0.0% (b) 0.2% (c) 0.4% (d) 0.6% Cu/Fe two composite powder in the 200Mpa and La2O3 content of 0~1.0% were respectively subjected to cold pressing under the pressure of the fracture surface of the SEM morphology as shown in Figure 5 (a) ~ (d). It can be seen from the fracture surface of the Cu/Fe composite powder that the fracture surface is layered, and the debris after the fracture becomes granular. This is due to the increase of the pressure and the deformation of the powder and the increase of the binding force between the powders, the structure of the pressed compacts is lamellar. From the edge of fault, it shows that the plastic deformation of Cu/Fe two composite powder compacts is higher. 3.3. Microstructure and properties of Cu20Fe80 alloy during microwave sintering Figure 6 (a) ~ (d) is the microstructure of La2O3 and 0~1.0% content of cold pressing strength of 200Mpa Cu20Fe80 alloy, Figure 7 is a ball milling 6h spectrum of Cu20Fe80 alloy surface can scan the contents of 0~1.0% and La2O3 cold compressive strength 200Mpa, in which the red phase is Fe rich phase, the green phase is Cu rich phase blue, La dispersed in iron matrix. Table 1 is the density and hardness of Cu20Fe80alloy with La2O3 content of 0~1.0% and cold pressing strength of 200Mpa. With the increase of La2O3 content, the density and hardness increased first and then decreased, and reached the maximum at 0.2%.Microstructure of Cu20Fe80 alloy by thicker lamellar black and grey hue in the La2O3 phase, the content is more than 0.4% layer distribution is not uniform, the surface contains a large number of pores (see figure 6c-d). With the increase of La2O3 content of Cu20Fe80 alloy relative density and hardness decrease.

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ACMME 2017 IOP Publishing IOP Conf. Series: Materials Science and Engineering 207 (2017) 012014 doi:10.1088/1757-899X/207/1/012014 1234567890

Table 1 The performance of Cu20Fe80 alloy Adding LaO3 6hdensity% Rockwell hardness

0.0% 86.21% 44.6

0.2% 92.35% 52

0.4% 90.87% 49.5

0.6% 88.77% 50.5

Fig.6 The microstructure of Cu20Fe80 alloy (a)0.0% (b)0.2% (c)0.4% (d)0.6%

Fig.7 The energy spectrum analysis of Cu20Fe80 alloy after ball milling 6h 4. Conclusion Cu20Fe80 alloy was prepared by mechanical alloying and cold pressing microwave sintering. The effects of La2O3 on Microstructure and properties of Cu20Fe80 alloy were investigated by SEM and XRD: (1) with the increase of La2O3 content, the mechanical alloying of Cu20Fe80 alloy composite powder was enhanced, and the density and hardness increased first and then decreased, while the strength and density of the alloy were the best; (2) the role of La2O3 in the Cu20Fe80 alloy, when the content is low can refine microstructure of alloy performance increase, but when the content is high, easy accumulation of rare earth oxides in the grain boundary, thus worsening the continuity of the matrix, the properties of the material is reduced. Acknowledgments Thanks to the Hebei Provincial Department of science and technology key projects (ZD2015006) and project 2015YF02 funding References [1] Su Wan Wan, Jiao Minghua, Wang Yuliang, Li Lingxin, Yin Yanguo. Influence of Cu on Microstructure and Tribological Properties of High - Boron Iron Based Bearing Materials [J]. Bearing, 2015,(1): 32. [2] Jia Chengchang. Sintering Metal OillessMetal World [J]. Bearing, 2011,22(1):28-34. [3] Fu Hanguang, Hu Hong. Progess of research on high boron wear resistant cast alloys[J]. Special Summary, 2005(3) :32. [4] Tong An, Fei Qin. Effects of the intermetallic compound microstructure on the tensile behavior of Sn3.0Ag0.5Cu/Cu solder joint under various strain rates[J]. Microelectronics Reliability,

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ACMME 2017 IOP Publishing IOP Conf. Series: Materials Science and Engineering 207 (2017) 012014 doi:10.1088/1757-899X/207/1/012014 1234567890

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2014 (54) : 932. Liu Y, Li B H, Li J, et al. Effect of Titanium on the ductilization of Fe-B alloys with high boron content [J]. Materials Letters, 2010, 64: 1299. X.L. Yan , M. Lin. J.Y.Wang. Equilibrium and kinetic surface segregations in Cu–Sn thin films [J]. Appl Phys A, 2013, (113) : 423.

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