A Analysis Of The Transverse Strength Of Ti-Based Matrix Composite Reinforced By Sic Fiber

World Journal of Engineering

A analysis of the transverse strength of Ti-based matrix composite reinforced by SiC fiber Zhao Bing, Hou HongLiang, Liao JinHua, JiangBo Beijing aeronatutical manufacturing technology research institute,Beijing,100024

Abstract: A new model is proposed to predict the ultimate strength of unidirectional titanium matrix composite (TMC) subjected to transverse loading at different temperatures, the mechanical property of interface is introduced into this model. Single-axis tensile experiment has been conducted at different temperature, the experimental transverse ultimate strength of TMC are agreed well the predictions of model. Keywords: titanium matrix composite, foil-fiber-foil, interface debonding strength, transverse strength

1. Introduction

Fiber reinforcd titanium matrix composites (SiCf/Ti) calculated by  t  kt a  q0 ,  t is the maximum tensile are under development for use in the next generation interface stress(169Mpa),  a is the tensile applied stress, aircraft engines for its high specific stiffness and strength kt is stress concentration factor of about 1.2 to 1.3, here in the fiber direction at elevated temperature. However, taken as 1.3, q0 is fiber clamping force, this is taken as the mechanical behavior of these composites under 300MPa. transverse loading is well behind their axial performance Fig.1 shows the analysis model, supposing that fiber [1-2] . A number of investigations have been performed on is in a rectangle arrangement, the SiCf/Ti composite

SiCf/Ti composites subjected to a transverse tensile. Reji. transverse tensile strength can be calculated by the [3] John proposed a model to predict the creep rupture life formula of  T   IC (10D f ) /  m (1 (10D f ) / )0 ,  T is of TMC subjected to transverse loading. However, the transverse ultimate tensile strength of composite,  IC is interface debonding strength is not considered in this interfacial debonding strength,  m is ultimate tensile model, therefore, a new analysis model is submitted by strength of the matrix D f is fiber diameter,  : thickness combining the interface debonding strength. The results of specimen. show that the new model has the advantages of accuracy, simplicity, and efficiency. 2. Materials and experiments SiC fiber used in this experiment is W-core SiC fiber made in china with a 1.05μm carbon coating. Ti6Al4V foil with a thickness of 0.1mm is applied as matrix. Foil- fiber-foil (FFF) method is a common method to fabricate

SiCf/Ti composites. However, several shortcomings limit Fig.1 Unit-Cell model the applications of FFF method, such as the low fibers 4. Results and discussion volume and poor fiber uniformity. Therefore, grooves are Assuming SiC fibers are in a rectangle arrangement, etched on the foil surface to prevent fibers from the SiCf/Ti6Al4V composite transverse tensile strength is swimming during the consolidation, then, these calculated at room temperature, 300℃ , 400 ℃ , 550 ℃ . Fig.2 prefabricated specimens are consolidated at shows the transverse tensile properties of experimental 920℃ /100MPa/1h. Single-fiber cruciform and transverse and calculated values without considering the thermal tensile specimens are cut from the panel after HIP process residual stress, the experimental transverse ultimate and performed on the Instron testing machine, the fracture tensile strength is 412MPa, 333MPa, 320MPa, 273MPa, surfaces are analyzed through SEM. the values is slightly lower than the calculated results, the 3. Analysis model maximum deviation in not more than 3.5%. It indicates According to the tensile experimental result of that the calculation method used in this article is an cruciform specimen, interface debonding strength can be

53 World Journal of Engineering accurate model for calculating the transverse tensile (a) RT (b) 300℃ strength.

(c) 400℃ (d) 550 ℃ Fig.4 Fracture surface of transverse tensile specimens at Fig.2 Transverse tensile strength comparison between different temperature calculated and experimental values 5. Conclusions 4.1. Microstructure and fracture analysis A modified FFF method d of notched foils is adapted

Fig.3 shows the microstructure of interfacial region to fabricate SiCf/Ti6Al4V composite, a very uniform fiber after 960℃ /200MPa/4h. It is evident that the interfacial distribution and sound fiber/matrix interface are obtained reaction layer with a thickness of 2μm does not exist any at 920℃ /100MPa/1h. micro-defects. Fig.4 shows the transversal fracture Single-fiber cruciform are used to test the fiber/ surface of different temperature. At room temperature, matrix interface debonding strength, the interface fibers fracture occurred and broken fiber remains on the debonding strength of as fabricated SiCf/Ti6Al4V made fracture surface because of the incompletely strip of of china fibers is 169MPa.Calculation model used in this fiber/matrix interface. At 300℃ , the fiber is not broken article calculates the transverse tensile strength after tensile, but the interfacial reaction layer and the fiber accurately, the maximum deviation in not more than 3.5% did not completely stripped, leaving a part of interfacial between experimental values and calculated results. reaction layer on the fiber surface. At 400℃and 550℃ , the fiber/matrix interface has completely stripped, the Reference stripping occurs mainly on the interface of 1. A. Vassel, Continuous fibere reinforced titanium and matrix/reaction. As seen above, with the increase of aluminium composites: a comparison, Materials temperature, thermal residual stresses in SiCf/Ti6Al4V Science and Engineering, 1999,A263(2),305–313. composite is relaxed, which making the fiber/matrix 2. C.M. Ward-Close, Advances in the fabrication of interface is more prone to debond. titanium metal matrix composite, Materials Science and Engineering, 1999,A263(2),314–318. 3. Reji John, M.Khobaib, Paul R.Smith, Rupture life of unidirectionally reinforced titanium matrix composites subjected to sustained transverse loading, Scripta Metallurgica of materials, 1995, 33(3), 473- 478. (a) Cross-sectional image (b) Interfacial region Fig.3 Microstructure of the interfacial region after 960℃/200MPa/4h