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Mechanical Properties of Tungsten Fiber Reinforced (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx Bulk Metallic Glass Composites
Rare Metal Materials and Engineering Volume 40, Issue 2, February 2011 Online English edition of the Chinese language journal Cite this article as: Rare Metal Materials and Engineering, 2011, 40(2): 0206-0208.
ARTICLE
Mechanical Properties of Tungsten Fiber Reinforced (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx Bulk Metallic Glass Composites Jiang Fei1, Chen Guang1, Chen Guoliang1 1
Wang Zhihua1,2,
Cao Yang1,
Cheng Jialin1,
2
Nanjing University of Science and Technology, Nanjing 210094, China; Tianjin University and Technology, Tianjin 300190, China
Abstract: Mechanical properties of (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx bulk metallic glass (BMG) matrix composites reinforced by tungsten fiber (Wf) were investigated by X-ray diffraction, scanning electron microscope (SEM) and so on. The results show that the matrix of the prepared composites remain amorphous after adding Nb with x=1, 3, 5 and 7, at%, and the compressive yield strength and plastic strain increase with the increase of Nb content. The composites with x=7 possess the excellent comprehensive properties, whose compressive yield strength and plastic strain reach 2450 MPa and 20%, respectively. Key words: BMG matrix composite; mechanical property; shear bands
Bulk metallic glass(BMG) matrix composite reinforced by extra particles and fibers or in-situ ductile crystalline phase is a new metal matrix composite. In 1990s, Leng et al[1] prepared the Ni91B2Si7 metallic glass ribbons matrix composite reinforced by ductile metal. Then, in 1998, R. D. Conner et al[2-5] also prepared the Zr-Ti-Cu-Ni-Be BMG matrix composite reinforced by tungsten fiber or steel fiber, and investigated their mechanical properties. The results showed that the compressive strain of the tungsten fiber reinforced BMG matrix composite is 900% more than that of monolithic BMG, and the fractural strain and fractural strain energy are also promoted by 13% and 18%, respectively. The research results with regard to ZrNb-based BMG of Ji Yingfei et al[6] indicated that adding Nb which has high melting point can promote the thermal stability of the metallic glass. F. Jiang et al’s[7] research on the (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx BMG found that adding Nb with x=0, 5, 11 and 13 can evidently promote the thermal stability and the compressive strength of the alloys, and the strength and plasticity of the alloys are more than 2000 MPa and 17%, respectively, which benefits from multiple shear bands in-
duced by ductile crystalline phase dispersing in the BMG matrix. Wang Meiling et al[8] investigated the interface of the tungsten fiber reinforced ZrTiCuNiBeNb BMG matrix composite, and their results indicated that adding Nb into the matrix alloy can not only depress the W-Zr interface reaction and the diffusion of Zr into the tungsten fiber, but also promote the solution of tungsten in the matrix alloy, increasing the hardness and elastic modulus of the interface with respect to the matrix alloy by complete infiltration and mutual diffusion between metallic glass and tungsten fiber; meanwhile, the cracks in the matrix cross over the interface into the reinforcements because of the increasing of interface strength, so that no crack is along the interface. Therefore, adding Nb can promote the stability and the interface strength of the matrix, and enhance the overall performance of the composites. In this paper, we investigated the effects of adding Nb in the matrix of tungsten fiber reinforced (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composite on the mechanical behaviors.
1 Experimental
Received date: March 05, 2010 Foundation item: National Natural Science Foundation of China (50871054); Research Fund for the Doctoral Program of Higher Education of China (20093219110035) Corresponding author: Jiang Fei, Candidate for Ph. D., Engineering Research Center of Materials Behavior and Design, Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094, P. R. China; Chen Guang, Professor, Tel: 0086-25-84315159, E-mail: [email protected] Copyright © 2011, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.
206
Jiang Fei et al. / Rare Metal Materials and Engineering, 2011,40(2): 0206−0208
The ingots of (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx alloy with x=1, 3, 5 and 7, at%, were prepared by arc melting a mixture of pure metal elements (>99.9%) in titanium-gettered argon atmosphere, used as the matrix of the composites. Tungsten fibers with a nominal diameter of 0.25 mm were straightened and cut into 100 mm lengths. The tungsten fibers were cleaned in an ultrasonic bath of acetone. 60% (volume fraction) of the tungsten fibers was packed in a quartz tube with 8 mm diameter, and then was cast in a resistive furnace by melting the ingots, followed by pressure infiltration. After 20 min of pressurization, the tubes were quenched in the mixture of ice and water. Complete details of the casting process can be found in Ref. [3]. X-ray diffraction (XRD) (Rigaku D/max 2038) was performed to analyze the phase structure of composite samples by monochromatic Cu Kα radiation with a 2θ range of 20° to 80°. Using a CSS-44200 testing machine compression tests were performed on the composite samples with 4 mm in diameter and 8 mm in length. The mechanical properties were obtained at a strain rate of 2×10-3 s-1 at room temperature. A JEOL/EO JSM-5900 scanning electron microscope (SEM) was used to observe the lateral surface morphology of compressed samples.
2
Results
Fig.1 shows the X-ray diffraction patterns of the Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x=1, 3, 5 and 7. The XRD patterns of the 4 composite samples exhibit a broad diffraction peak in the 2θ range of 35° through 45°, as the typical characteristic peak for the BMG structure. The sharp peaks at the 2θ=40.26°, 58.20° and 73.08° are the three characteristic peaks of tungsten, relative to (110), (200) and (211) crystal plane, respectively. In addition, there is no other obvious crystal phase peak on the XRD patterns indicating that matrix of the composites remain the amorphous structure after adding Nb element. All the quasi-static compressive stress-stain curves of Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x=1, 3, 5 and 7 samples show three stages, i.e. elastic deformation, perfectly plastic deformation and final fracture, seen in Fig.2,
x=1
50
60
70
Generally speaking, the two functions of the interface of the composites are force transfer and interdiction effect. On the one hand, the interface is transferring the force to the reinforcements, acting as the bridge between the matrix and the reinforcements; on the other hand, the interface with well-situated strength can prevent the spread of the cracks, stop the failure of the composite, and reduce the stress concentration. This means that the interface of the composite is closely relative to its mechanical behaviors. The research in Ref. [8] showed that adding Nb into the matrix of tungsten fiber reinforced BMG composites will obviously promote the interfacial strength. Thus, interfacial strength of (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx BMG composite reinforced by tungsten fiber increases with the increase of Nb content. In this way, on the one hand, the larger load can be transferred through the interface, resulting in improving the failure limit of the composites; on the other hand, as the interfacial strength increases, i.e., the stress limit interface withstands is improved, and cracks need bigger stress to pass through the interface. On the view of macroscopic, this behaves the increase of the yield strength of the composite. The ductile metal evenly distributed in the BMG matrix of composites not only prevents the propagation of the single shear band, but also promotes the generation of multiple shear bands. It is generally considered that the number of the shear bands is related to the plasticity of the materials, and a larger number of shear bands means bigger plasticity. In fact, seen from microscopic view, the main reason for generation of multiple shear bands is attributed to the existences of the interface between the BMG matrix and tungsten fiber. As seen
Engineering Stress/MPa
(211)
(200)
(110)
Intensity/a.u.
x=5 x=3
40
3 Discussions
3000
x=7
30
and the yield strengths of the samples are more than 2000 MPa, with the maximum strength up to 2450 MPa. Moreover, the compressive yield strength and plastic strain all increase with the increase of Nb content, and the maximum plastic strain is up to 20% with Nb adding of x=7. Therefore, adding of Nb element can obviously enhance the compressive properties of the Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites.
80
2500
x=5
x=7
x=3 x=1
2000 1500 1000 500 0
5%
Engineering Strain/%
2θ/(°) Fig.2 Quasi-static compressive stress-strain curves of Wf/ Fig.1 XRD patterns of the sample for Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x=1, 3, 5 and 7
(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x= 1, 3, 5 and 7
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Jiang Fei et al. / Rare Metal Materials and Engineering, 2011,40(2): 0206−0208
in Fig.3a, all the shear bands stop at the interface, and the direction of some shear bands changes to the symmetrical direction at the interface. Moreover, crossing shear bands generate when the spacing among tungsten fibers is relatively big, as shown in Fig.3b. The plasticity of the composite after yielding mainly depends on the interface, so long as interface can sustain the shearing stress in the BMG matrix, the interface do not fail, the composite can continue a plastic deformation. After adding Nb element, interfacial strength of the composite is improved; thus, the interface can undergo larger shearing stress, and the microscopic reflection takes on the concentrated crossing or symmetrical multiple shear bands. From the above, the plasticity is also obviously improved. It is found that the number of the shear bands will increase with the ina
crease of the Nb content in the SEM observation. It is relatively hard to find shear bands in the lateral of the composite sample with x=1, while the number of shear bands in the sample with x=7 is the greatest.
4 Conclusions 1) The matrix remains the amorphous structure in the tungsten fiber reinforced (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx BMG composite after adding Nb. 2) Adding Nb can improve the interfacial strength between BMG matrix and tungsten fiber, so that the yield strength of the composite is obviously enhanced; the yield strength and plastic strain of the composite with x=7 Nb are up to 2450 MPa and 20%, respectively.
References 1 Leng, Y.; Courtney, T. H. Journal of Materials Science, 1991, 26: 588 2 Conner, R. D.; Dandliker, R. B.; Johnson, W. L. Acta Materialia, 1998, 46(17): 6089 3 Dandliker, R. B.; Conner, R. D.; Johnson, W. L. Journal of Ma-
Amorphous alloy
terials Research, 1998, 13(10): 2839
W
4 Choi-Yim, H.; Conner, R. D.; Szuecs, F. Scripta Material, 2001,
300 μm b
45: 1039 5 Conner, R. D.; Dandliker, R. B.; Scruggs, V. International Journal of Impact Engineering, 2000, 24: 435 6 Ji, Yingfei; Ma, Xueming; Dong, Yuanda. Materials Science & Engineering, 2000, 18(3): 39 7 Jiang, F.; Chen, G.; Li, W. L. Metallurgical and Materials Trans-
W
actions A, 2008, 39A: 1812
Amorphous alloy
300 μm
8 Wang, Meiling; Hui, Xidong; Dong, Wei. The Chinese Journal of Nonferrous Metals, 2004, 14(10): 1632
Fig.3 Multi-shear bands on the flank of compressive samples for the composite amorphous alloy: (a) x=1 and (b) x=5
208
ARTICLE
Mechanical Properties of Tungsten Fiber Reinforced (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx Bulk Metallic Glass Composites Jiang Fei1, Chen Guang1, Chen Guoliang1 1
Wang Zhihua1,2,
Cao Yang1,
Cheng Jialin1,
2
Nanjing University of Science and Technology, Nanjing 210094, China; Tianjin University and Technology, Tianjin 300190, China
Abstract: Mechanical properties of (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx bulk metallic glass (BMG) matrix composites reinforced by tungsten fiber (Wf) were investigated by X-ray diffraction, scanning electron microscope (SEM) and so on. The results show that the matrix of the prepared composites remain amorphous after adding Nb with x=1, 3, 5 and 7, at%, and the compressive yield strength and plastic strain increase with the increase of Nb content. The composites with x=7 possess the excellent comprehensive properties, whose compressive yield strength and plastic strain reach 2450 MPa and 20%, respectively. Key words: BMG matrix composite; mechanical property; shear bands
Bulk metallic glass(BMG) matrix composite reinforced by extra particles and fibers or in-situ ductile crystalline phase is a new metal matrix composite. In 1990s, Leng et al[1] prepared the Ni91B2Si7 metallic glass ribbons matrix composite reinforced by ductile metal. Then, in 1998, R. D. Conner et al[2-5] also prepared the Zr-Ti-Cu-Ni-Be BMG matrix composite reinforced by tungsten fiber or steel fiber, and investigated their mechanical properties. The results showed that the compressive strain of the tungsten fiber reinforced BMG matrix composite is 900% more than that of monolithic BMG, and the fractural strain and fractural strain energy are also promoted by 13% and 18%, respectively. The research results with regard to ZrNb-based BMG of Ji Yingfei et al[6] indicated that adding Nb which has high melting point can promote the thermal stability of the metallic glass. F. Jiang et al’s[7] research on the (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx BMG found that adding Nb with x=0, 5, 11 and 13 can evidently promote the thermal stability and the compressive strength of the alloys, and the strength and plasticity of the alloys are more than 2000 MPa and 17%, respectively, which benefits from multiple shear bands in-
duced by ductile crystalline phase dispersing in the BMG matrix. Wang Meiling et al[8] investigated the interface of the tungsten fiber reinforced ZrTiCuNiBeNb BMG matrix composite, and their results indicated that adding Nb into the matrix alloy can not only depress the W-Zr interface reaction and the diffusion of Zr into the tungsten fiber, but also promote the solution of tungsten in the matrix alloy, increasing the hardness and elastic modulus of the interface with respect to the matrix alloy by complete infiltration and mutual diffusion between metallic glass and tungsten fiber; meanwhile, the cracks in the matrix cross over the interface into the reinforcements because of the increasing of interface strength, so that no crack is along the interface. Therefore, adding Nb can promote the stability and the interface strength of the matrix, and enhance the overall performance of the composites. In this paper, we investigated the effects of adding Nb in the matrix of tungsten fiber reinforced (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composite on the mechanical behaviors.
1 Experimental
Received date: March 05, 2010 Foundation item: National Natural Science Foundation of China (50871054); Research Fund for the Doctoral Program of Higher Education of China (20093219110035) Corresponding author: Jiang Fei, Candidate for Ph. D., Engineering Research Center of Materials Behavior and Design, Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094, P. R. China; Chen Guang, Professor, Tel: 0086-25-84315159, E-mail: [email protected] Copyright © 2011, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.
206
Jiang Fei et al. / Rare Metal Materials and Engineering, 2011,40(2): 0206−0208
The ingots of (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx alloy with x=1, 3, 5 and 7, at%, were prepared by arc melting a mixture of pure metal elements (>99.9%) in titanium-gettered argon atmosphere, used as the matrix of the composites. Tungsten fibers with a nominal diameter of 0.25 mm were straightened and cut into 100 mm lengths. The tungsten fibers were cleaned in an ultrasonic bath of acetone. 60% (volume fraction) of the tungsten fibers was packed in a quartz tube with 8 mm diameter, and then was cast in a resistive furnace by melting the ingots, followed by pressure infiltration. After 20 min of pressurization, the tubes were quenched in the mixture of ice and water. Complete details of the casting process can be found in Ref. [3]. X-ray diffraction (XRD) (Rigaku D/max 2038) was performed to analyze the phase structure of composite samples by monochromatic Cu Kα radiation with a 2θ range of 20° to 80°. Using a CSS-44200 testing machine compression tests were performed on the composite samples with 4 mm in diameter and 8 mm in length. The mechanical properties were obtained at a strain rate of 2×10-3 s-1 at room temperature. A JEOL/EO JSM-5900 scanning electron microscope (SEM) was used to observe the lateral surface morphology of compressed samples.
2
Results
Fig.1 shows the X-ray diffraction patterns of the Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x=1, 3, 5 and 7. The XRD patterns of the 4 composite samples exhibit a broad diffraction peak in the 2θ range of 35° through 45°, as the typical characteristic peak for the BMG structure. The sharp peaks at the 2θ=40.26°, 58.20° and 73.08° are the three characteristic peaks of tungsten, relative to (110), (200) and (211) crystal plane, respectively. In addition, there is no other obvious crystal phase peak on the XRD patterns indicating that matrix of the composites remain the amorphous structure after adding Nb element. All the quasi-static compressive stress-stain curves of Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x=1, 3, 5 and 7 samples show three stages, i.e. elastic deformation, perfectly plastic deformation and final fracture, seen in Fig.2,
x=1
50
60
70
Generally speaking, the two functions of the interface of the composites are force transfer and interdiction effect. On the one hand, the interface is transferring the force to the reinforcements, acting as the bridge between the matrix and the reinforcements; on the other hand, the interface with well-situated strength can prevent the spread of the cracks, stop the failure of the composite, and reduce the stress concentration. This means that the interface of the composite is closely relative to its mechanical behaviors. The research in Ref. [8] showed that adding Nb into the matrix of tungsten fiber reinforced BMG composites will obviously promote the interfacial strength. Thus, interfacial strength of (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx BMG composite reinforced by tungsten fiber increases with the increase of Nb content. In this way, on the one hand, the larger load can be transferred through the interface, resulting in improving the failure limit of the composites; on the other hand, as the interfacial strength increases, i.e., the stress limit interface withstands is improved, and cracks need bigger stress to pass through the interface. On the view of macroscopic, this behaves the increase of the yield strength of the composite. The ductile metal evenly distributed in the BMG matrix of composites not only prevents the propagation of the single shear band, but also promotes the generation of multiple shear bands. It is generally considered that the number of the shear bands is related to the plasticity of the materials, and a larger number of shear bands means bigger plasticity. In fact, seen from microscopic view, the main reason for generation of multiple shear bands is attributed to the existences of the interface between the BMG matrix and tungsten fiber. As seen
Engineering Stress/MPa
(211)
(200)
(110)
Intensity/a.u.
x=5 x=3
40
3 Discussions
3000
x=7
30
and the yield strengths of the samples are more than 2000 MPa, with the maximum strength up to 2450 MPa. Moreover, the compressive yield strength and plastic strain all increase with the increase of Nb content, and the maximum plastic strain is up to 20% with Nb adding of x=7. Therefore, adding of Nb element can obviously enhance the compressive properties of the Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites.
80
2500
x=5
x=7
x=3 x=1
2000 1500 1000 500 0
5%
Engineering Strain/%
2θ/(°) Fig.2 Quasi-static compressive stress-strain curves of Wf/ Fig.1 XRD patterns of the sample for Wf/(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x=1, 3, 5 and 7
(Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx composites with x= 1, 3, 5 and 7
207
Jiang Fei et al. / Rare Metal Materials and Engineering, 2011,40(2): 0206−0208
in Fig.3a, all the shear bands stop at the interface, and the direction of some shear bands changes to the symmetrical direction at the interface. Moreover, crossing shear bands generate when the spacing among tungsten fibers is relatively big, as shown in Fig.3b. The plasticity of the composite after yielding mainly depends on the interface, so long as interface can sustain the shearing stress in the BMG matrix, the interface do not fail, the composite can continue a plastic deformation. After adding Nb element, interfacial strength of the composite is improved; thus, the interface can undergo larger shearing stress, and the microscopic reflection takes on the concentrated crossing or symmetrical multiple shear bands. From the above, the plasticity is also obviously improved. It is found that the number of the shear bands will increase with the ina
crease of the Nb content in the SEM observation. It is relatively hard to find shear bands in the lateral of the composite sample with x=1, while the number of shear bands in the sample with x=7 is the greatest.
4 Conclusions 1) The matrix remains the amorphous structure in the tungsten fiber reinforced (Zr41.2Ti13.8Cu12.5Ni10Be22.5)100-xNbx BMG composite after adding Nb. 2) Adding Nb can improve the interfacial strength between BMG matrix and tungsten fiber, so that the yield strength of the composite is obviously enhanced; the yield strength and plastic strain of the composite with x=7 Nb are up to 2450 MPa and 20%, respectively.
References 1 Leng, Y.; Courtney, T. H. Journal of Materials Science, 1991, 26: 588 2 Conner, R. D.; Dandliker, R. B.; Johnson, W. L. Acta Materialia, 1998, 46(17): 6089 3 Dandliker, R. B.; Conner, R. D.; Johnson, W. L. Journal of Ma-
Amorphous alloy
terials Research, 1998, 13(10): 2839
W
4 Choi-Yim, H.; Conner, R. D.; Szuecs, F. Scripta Material, 2001,
300 μm b
45: 1039 5 Conner, R. D.; Dandliker, R. B.; Scruggs, V. International Journal of Impact Engineering, 2000, 24: 435 6 Ji, Yingfei; Ma, Xueming; Dong, Yuanda. Materials Science & Engineering, 2000, 18(3): 39 7 Jiang, F.; Chen, G.; Li, W. L. Metallurgical and Materials Trans-
W
actions A, 2008, 39A: 1812
Amorphous alloy
300 μm
8 Wang, Meiling; Hui, Xidong; Dong, Wei. The Chinese Journal of Nonferrous Metals, 2004, 14(10): 1632
Fig.3 Multi-shear bands on the flank of compressive samples for the composite amorphous alloy: (a) x=1 and (b) x=5
208