between commercially pure titanium and Copper-Zinc (brass) is applied. The microstructure of the diffusion zone has been analyzed by optical and scanning ...
Intrinsic Modification and Interfacial Behavior in a TitaniumCopper Metal Matrix Composite Yasser Fouad1 , and Bakr M. Rabeeh 2 1- Ass. Prof.: Engineering and Materials Science Dept. German University in Cairo, GUC. 2- Prof. Dr.: Engineering and Materials Science Dept. German University in Cairo, GUC. Abstract—The application of hot uniaxial pressing has been carried out in the temperature range of 750–950 °C for 0.5, 1 and 2 h at uniaxial pressure of 3 MPa in vacuum. Ti/Cu-Zn/Ti foil-foil layup are hot pressed for a lamellar composite structure symmetrically arranged. Inter diffusion bonding between commercially pure titanium and Copper-Zinc (brass) is applied. The microstructure of the diffusion zone has been analyzed by optical and scanning electron microscopy (SEM). The inter diffusion of the diffusing species across the interface has been evaluated by energy dispersive X-ray spectroscopy EDX. The reaction products formed at the interface have been identified by X-ray diffraction technique. It has been observed that the diffusion zone is dominated by the presence of the low melting depressant (LMD) Zn that segregate into Ti side and the solid solution of β-Ti (solutes are Zn, Cu and Ni) close to the titanium. The presence of Cu and Zn and Ti has been found in the interphase reaction zone. It has been observed that the interfacial bond strength (∼200 MPa) is highest for the couple processed at 800 °C and this value decreases with rise in joining temperature. The variation of strength of the transition joints is co-related with the microstructural characteristics of the diffusion zone. The application of brass (Cu-Zn) interlayer bonding of pure titanium introduced with different micro constituents. The control of interphase is dominant for composite processing. Keywords— Diffusion joint; Inter-diffusion; Ti-Cu; Micro mechanical Modeling I.
INTRODUCTION
Titanium matrix composites (TMCs) reinforced with copperzinc (brass) are considered to be attractive candidate materials for structural components in automotive and aerospace applications. TMCs show superior mechanical properties (such as tensile, creep and fatigue) compared to unreinforced titanium alloys [1]. However, the serial application of titanium matrix composites is still very limited due to cost reasons and processing difficulties. Potential applications may be found in aircraft components where high specific strength and stiffness are needed in combination with heat resistance. Current processes are using unidirectional or hot isostatical pressing for the consolidation of the composite material [2]. The pressing of the material leads to shrinkage, distortion in the worst case. To diminish these difficulties a non-traditional
process has been developed for the production of titanium reinforced metal matrix in a lamellar structure. The objective is to engineer new composite materials that include using nontraditional element in a titanium (Ti) metal-matrix. The nontraditional used element is copper-zinc (brass). This new composite material is considered to be advantageous over pure Ti in many aspects. The creation of this new material allows for improved properties over those of pure Ti. The production steps are part of the successful creation of the new composite material. The creation of this particular material makes it unique compared to other metal matrix composites. Many previous work based on bonding of similar and dissimilar materials has shown minor limitations, especially delamination [3-5]. Hot uniaxial pressing has been carried out in the temperature range of 750–950 °C for 0.5, 1 and 2 h at uniaxial pressure of 3 MPa in vacuum. Foil-foil layup of Ti/Cu-Zn/Ti are hot pressed for a lamellar composite structure symmetrically arranged. Inter diffusion bonding between commercially pure titanium and Copper-Zinc (brass) is dominant with alloy segregation[6-8]. The inter-diffusion of Ti-Cu may introduce intrinsic modification of pure Ti. The microstructure of the diffusion zone has been analyzed by optical and scanning electron microscopy (SEM). The inter diffusion of the diffusing species across the interface has been evaluated by energy dispersive X-ray spectroscopy EDX. The reaction products formed at the interface have been identified by X-ray diffraction technique. It has been observed that the diffusion zone is dominated by the presence of the low melting depressant (LMD) Zn that segregate into Ti side and the solid solution of β-Ti (solutes are Zn, Cu and Ni) close to the titanium. The presence of Cu and Zn and Ti has been found in the interphase reaction zone. It has been observed that the interfacial bond strength (∼200 MPa) is highest for the couple processed at 800 °C and this value decreases with rise in joining temperature [850oC]. The variation of strength of the transition joints is co-related with the microstructural characteristics of the diffusion zone in a nonlinear stress-strain diagram. The control of interface/interphase is dominant for composite processing. Besides, the application of brass (CuZn) interlayer bonding of pure titanium introduced with different micro constituents
ICET 2012
II- RESULTS AND DISCUSSION The processing of symmetrically applied lamellar structure of Ti/Brass/Ti interlayers via hot uniaxial pressing in a special metallic die. 3 mm sheet of both titanium and brass are hot uniaxial pressed under 3 MPa press at different temperatures 750–950 °C for 0.5, 1 and 2 h. The process is conducted to fulfill complete air bleeding that consider to be as in in vacuum. 3-different group of samples are prepared at 700, 800 and 8500C for 30 minutes. Figure 1 presents the lay-up of foil-foil technique that conducted [at left] to conclude the final shape [at right]. The control of interface/interphase is dominant for composite processing. Besides, the application of brass (Cu-Zn) interlayer bonding of pure titanium introduced with different micro constituents. The optical microscopy of the final structure is captured and presented in Figure 2. Ti/brass MMC with clear interface/interphase and no delamination at 700 oC for 30 minutes holding time [the first set of samples]. In addition, scanning electron microscopy, SEM, is conducted to the sample Pressed at 700oC for 30 minutes and presented in Figure 3. The structure reveals clear bonding with minor interface/interphase that presented in Figure 4. 3-point are selected for energy dispersive x-ray spectroscopy A, B and C and presented in Figures 5, 6 and 7 respectively. Figure 5 presents EDX analysis at point A that resolves pure titanium with minor elements. of a sample that pressed at 700oC for 30 minutes. Figure 6 presents EDX analysis at point B, resolve inter diffusion of both Cu-Zn and Ti of sample pressed at 700oC for 30 minutes. Figure 7 presents EDX analysis at point C, resolve Cu-Zn with Ti of sample pressed at 700oC for 30 minutes. The second set of sampled are conducted at 800 oC for 30 minutes holding time. Figure 8 presents optical microscopy of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes. Figure 9 presents SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes [low mag.]. Figure 10 presents SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes [high mag.]. Figure 11 presents SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes [high mag.]. Figure 12 presents SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes [high mag.]. Figure 13 presents SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes [high mag.]. Figure 14 and 15 present SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes with ore magnifications. It resolves two different interphase with localized growth through Ti [Fig. 15]. Figure 16 presents 3-points EDX A, B and C in SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes. The EDX analysis are presented in Figures 17, 18, and 19 respectively for A, B, and C points.
In addition to microstructural analysis, mechanical characterizations are conducted on the three different samples. Figure 20 presents stress-strain diagram of a pure Titanium sample for comparison. Traditional strain diagram is obtained with clear yielding point UTS, and fracture point. Nontraditional stress strain diagrams are obtained for Ti/brass MMC at 700, 800, and 850oC and presented in Figure 21, 22, and 23 respectively. However, ductility decrease compared to pure Titanium, material properties increases at 800oC but reduced at 850oC. III- CONCLUSIONS Hot uniaxial pressing has been carried out in the temperature range of 750–950 °C for 0.5, 1 and 2 h at uniaxial pressure of 3 MPa in vacuum. Ti/Cu-Zn/Ti MMC is established at 800oC for the best microstructural properties and mechanical properties. A lamellar composite structure with symmetrically arranged plies is introduced with control interface/interphase. The kinetics of interphase is introduced through inter diffusion mechanisms that induce chemical and mechanical bonding between commercially pure titanium and Copper-Zinc (brass). The microstructure of the diffusion zone has been analyzed by scanning electron microscopy (SEM) and EDX. The reaction products formed at the interface have been identified by X-ray diffraction technique. It has been observed that the diffusion zone is dominated by the presence of the low melting depressant (LMD) Zn that segregate into Ti side and the solid solution of β-Ti (solutes are Zn, Cu and Ni) close to the titanium. The presence of Cu and Zn and Ti has been found in the interphase reaction zone. It has been observed that the interfacial bond strength (∼200 MPa) is highest for the couple processed at 800 °C and this value decreases with rise in joining temperature. The variation of strength of the transition joints is co-related with the microstructural characteristics of the diffusion zone. The application of brass (Cu-Zn) interlayer bonding of pure titanium introduced with different micro constituents. The control of interphase is dominant for composite processing.
ICET 2012
Figure 1. Ti/brass/Ti foil lay up in symmetrically shape [left] to be hot pressing uniaxial for the final shape [right]
Figure 5. EDX analysis at point A, resolve pure titanium with minor elements. of sample pressed at 700oC for 30 minutes.
Figure 2. Optical microscopy of Ti/brass MMC with clear interface/interphase and no delamination at 700oC for 30 minutes.
Figure 6. EDX analysis at point B, resolve inter diffusion of both Cu-Zn and Ti of sample pressed at 700oC for 30 minutes
Figure 3. SEM Ti/brass MMC with clear interface/interphase and no delamination at 700oC for 30 minutes.
Figure 4. SEM Ti/brass MMC with clear interface/interphase and no delamination at 700oC for 30 minutes.
Figure 7. EDX analysis at point C, resolve Cu-Zn with Ti of sample pressed at 700oC for 30 minutes
Figure 8. Optical microscopy of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes.
ICET 2012
Figure 9. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
Figure 13. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
Figure 10. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
Figure 14. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
Figure 11. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
Figure 15. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
Figure 12. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
Figure 16. SEM of Ti/brass MMC with clear interface/interphase and no delamination at 800oC for 30 minutes
ICET 2012
Figure 17. EDX analysis at point A, resolve pure titanium with minor elements. of sample pressed at 800oC for 30 minutes.
Figure 21. Stress-strain diagram of Ti/brass MMC (700°C – 45min) results:
Figure 18. EDX analysis at point B, resolve inter diffusion of both Cu-Zn and Ti of sample pressed at 800oC for 30 minutes
Figure 22. Stress-strain diagram of Ti/brass MMC (800°C – 30min)
Figure 19. EDX analysis at point C, resolve Cu-Zn with Ti of sample pressed at 800oC for 30 minutes
Figure 21. Stress-strain diagram of Ti/brass MMC (850°C – 30min):
REFERENCES [1]
[2]
Figure 20. Stress-strain diagram of pure Titanium
[3]
Mall, S., Fecke, T., Foringer, M.A., in ―Titanium Matrix Composites: Mechanical Behavior‖. Eds.: S. Mall T. ,Nicholas, Technomic Publishing Co, Inc.: Lancaster, Basel, pp. 1-22, 1998. Leyens, C., Hausmann, J., Kumpfert, J., in ―Titanium and Titanium Alloys‖. Eds.: C. Leyens, M. Peters, Wiley-VCH, pp. 305-331, 2003. B. M. Rabeeh, M. E. Shamekh, and M. T. Sallam, ―Low Temperature Transient Liquid Phase Bonding of Copper-Aluminum Laminated Composites", Proceeding of the 9th Applied Mechanics and Mechanical Engineering Conference, AMME Conf. 16-18 May, 2000, Cairo, Egypt.
ICET 2012
[4]
[5]
[6] [7]
[8]
Li, M.G., D.Q. Sun, X.M. Qiu, D.X. Sun, S.Q. Yin Effects of laser brazing parameters on microstructure and properties of TiNi shape memory alloy and stainless steel joint - Materials Science and Engineering A 424 (2006) p. 17–22 Bakr Mohamed Rabeeh, ―Macroscopic and Microscopic Aspects Observed in Composite Processing For Shape Memory Alloy‖, 14th International Conference on Applied Mechanics and Mechanical Engineering AMME-14. Proceedings of the 14th AMME-14 Conference, 25-27 May, 2010. Worden K. Bullough W. A., Haywood J., Smart technologies, World Scientific (2003), pp.109–135 Hodgson D. E. , Shape Memory Applications, Inc., Wu M. H., Memry Technologies, and Biermann R. J., Harrison Alloys, Inc., http://web.archive.org/ web/20030605085042/ http://www. smainc.com/SMAPaper.html Van Humbeeck J., Cederstrom J., ―The present state of shape memory materials and barriers still to be overcome‖, The first international conference on shape memory and superelastic technologies, March 1994, pp. 1–6.
ICET 2012
