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The interaction of reaction bonded silicon carbide and INCONEL 600 with a nickel based brazing alloy
Zirconia toughened alumina (ZTA) ceramics Wang, J. and Stevens, R. Journal o f Materials Science Vo124 No 10 (1989) pp 3421-3440 Zirconia - toughened alumina (ZTA) ceramics may be regarded as a new generation of toughened ceramics. A review of literature concerning fabrication, mechanical properties and toughening mechanisms of ZTA's is presented. The critical microstructural dependence of mechanical properties of ZTA's is discussed, and the control of microstructures by fabrication routes, with specific applications in mind, is examined. The possible future development of ZTA is considered, with emphasis on property measurement, reinforcement and use at high temperatures.
GENERAL Accelerated characterization of a chopped fiber composite using a strain energy failure criterion Yen, S-C and Morris, D.H. Polymer Composites Vo110 No 4 (1989) pp 249-255 Using short term creep data a modified power law equation (Findley's equation) was used to successfully predict long term creep response. When this was combined with a strain energy based failure criterion, the creep rupture could also be predicted. It was found that for a given temperature the strain energy density associated with creep rupture was constant. The interaction of reaction bonded silicon carbide and INCONEL 600 with a nickel based brazing alloy McDermid, J.R., Pugh, M.D. and Drew, R.A.L. Metallurgical Transactions A Vol 20 A No 5 (1989) pp 1803-1809 Two methods of joining reaction bonded silicon carbide (RBSC) to INCONEL 600 are investigated. Firstly, a direct welding technique is used, employing a commercial nickel based brazing alloy (BNi-5) as a filler material. Secondly, a composite layer interjoining technique is used, employing intimate mixtures of or-SiC and BNi-5 powders. Specimens are studied by optical and scanning electron microscopy, electron probe microanalysis and differential thermal analysis. In both cases the liquid filler metal forms a Ni-Si liquid with the free Si in the RBSC which reacts with the SiC component of RBSC to form low melting point constituents. The joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is found to be unfeasible due to the reaction of the filler metal with the ceramic, thus degrading the high temperature properties of the base material. On the forced motions of antisymmetric cross-ply laminated plates Khdeir, A.A. and Reddy, J.N. International Journal of Mechanical Sciences Vol 31 No 7 (1989) pp 499-510 The transient response of an antisymmetric cross-ply rectangular plate under simply supported boundary conditions was studied when subjected to sinusoidally distributed transverse and blast (exponential) loading in the time domain. Dynamic solutions of the classical, first and third order laminate plate theories were obtained and the numerical
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solutions compared. The effects of anisotropy, the number of layers and transverse shear deformation are shown. The classical solution was shown to underestimate the transverse shear deflection. First and third order solutions yielded almost identical results. Prediction of variation of upper critical magnetic field of Nb2Sn superconducting composites as a function of applied stress at room temperature Ochiai, S. and Osamura, S. Acta Metallargica Vo137 No 9 (1989) pp 2539-2549 A model was proposed to predict the variation of upper critical magnetic field of bronze processed Nb2Sn superconducting composites as a function of applied stress on composites at room temperature. Calculations based upon the model developed agreed fairly well with those determined from experimental results. These results were attained on niobium filaments in a Cu-Sn alloy surrounded with a niobium barrier and then pure copper stabiliser. The upper critical magnetic field increased to a maximum with stress. The sensitivity of the ratio of the upper critical magnetic field, for the strained to the unstrained composite, increased with the level of the tin in bronze. A re-examination of the analysis of toughening in brittle-matrix composites Thouless, M.D. Acta Metallurgica Vo137 No 9 (1989) pp 2297-2304 The J-integral, as used for calculating the toughness of a brittle-fibre reinforced composite, was considered with respect to the role of interfacial friction. Upper and lower bounds were calculated for the toughness with the J-integral. These were determined by considering friction alone and a complete consideration of the losses associated with the mechanics of fibre failure respectively. A method was presented by which the J-integral could be combined with statistical models of fibre failure to incorporate the effects of fibre pull-out on the composites toughness. Stress fields in a composite material by means of a non-classical approach Ardic, E.S., Santare M.H. and Chou T.W. International Journal o f Engineering Sciences Vo127 No 11 (1989) pp 1397-1405 In this paper a method was developed to determine the separate stress field expressions for the materials in a two dimensional bimaterial composite body under elastic deformation. The model combines classical elasticity with nonlocal continuum mechanics and takes into account the effects of inhomogeneity and anisotropy. The solution for a condition of plane strain was compared with that obtained from classical models.
METAL MA TRICES The application of the Eshclby method of internal stress determination to short fibre metal matrix composites Withers, P.J., Stobbs, W.M. and Pendersen, O.B. Acta Metallurgica Vo137 No 11 (1989) pp 3061-3084
The prediction of mechanical properties of short fibre composites was theoretically dealt with using Elshelby's equivalent inclusion approach. The elastic, thermoelastic and plastic behaviour of this group of composites were predicted and compared with the experimentally determined results for the AI/SiC system. The role of relaxation phenomena in the development of internal stresses was determined. It was also confirmed that it was possible to understand the energctics and the resultant stress distribution between the two phases within the framework of the Elshelby model. Calculation of minimum pressure for liquid metal infiltration of a fibre array Nourbakhsh, S., Liang, F.L. and Margolin, H. Metallurgical Transactions A Vo120 A No 9 (1989) pp 1861-1866 Equations are derived in order to evaluate the effects of capillary forces on the pressure differential required for the infiltration of square and hexagonal arrays of parallel fibres by a liquid. Three different models are considered; i) unidirectional flow normal to the fibres, ii) bidirectional flow normal to the fibres and iii) three-dimensional flow. The lowest predicted infiltration pressure is derived from the three-dimensional model. Required pressure differentials for infiltration derived from models based on work of immersion are compared with the pressure differentials obtained from models based on capillary forces. Calculations of minimum pressure for liquid metal infiltration of a fibre array Nourbakhsh, S., Liang, F.L. and Margolin H. Metallurgical Transactions A Vol 20A No 9 (1989) pp 1861-1875 Equations have been derived which take into account the effect of capillary forces on the pressure differential required for liquid metal infiltration of a fibre array. Models were developed for both square and hexagonal arrays of fibres subjected to unidirectional, bidirectional and three-dimensional metal infiltration. The minimum pressure differential was calculated to be that for three dimensional infiltration of a hexagonal array. A comparison was made between models based on the work required for fibre immersion and the present model which is based on the work required to overcome the capillary forces. Crack bridging by uncracked ligaments during fatigue - crack growth in SiC reinforced aluminium alloy composites Shang, J.K. and Ritchie, R.O. Metallurgical Transactions A VoI 20 A No 5 pp 897-908 The role of crack tip shielding in enhancing the toughness of metal matrix composites is examined. Based on the study of crack bridging by uncracked ligaments in a powder metallurgy AI-Zn-Mg-Cu matrix alloy reinforced with 15-20 wt% SiC particulate, simple models are developed to predict the magnitude of crack tip shielding during fatigue crack growth. It is found that the production of uncracked ligaments is related to the fracture events occurring ahead of the crack-tip, such as the cracking of SiC particles, and that at higher crack growth rates bridging is seen to predominate since SiC particle fractures are significant only at higher stress intensity levels.
GENERAL Accelerated characterization of a chopped fiber composite using a strain energy failure criterion Yen, S-C and Morris, D.H. Polymer Composites Vo110 No 4 (1989) pp 249-255 Using short term creep data a modified power law equation (Findley's equation) was used to successfully predict long term creep response. When this was combined with a strain energy based failure criterion, the creep rupture could also be predicted. It was found that for a given temperature the strain energy density associated with creep rupture was constant. The interaction of reaction bonded silicon carbide and INCONEL 600 with a nickel based brazing alloy McDermid, J.R., Pugh, M.D. and Drew, R.A.L. Metallurgical Transactions A Vol 20 A No 5 (1989) pp 1803-1809 Two methods of joining reaction bonded silicon carbide (RBSC) to INCONEL 600 are investigated. Firstly, a direct welding technique is used, employing a commercial nickel based brazing alloy (BNi-5) as a filler material. Secondly, a composite layer interjoining technique is used, employing intimate mixtures of or-SiC and BNi-5 powders. Specimens are studied by optical and scanning electron microscopy, electron probe microanalysis and differential thermal analysis. In both cases the liquid filler metal forms a Ni-Si liquid with the free Si in the RBSC which reacts with the SiC component of RBSC to form low melting point constituents. The joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is found to be unfeasible due to the reaction of the filler metal with the ceramic, thus degrading the high temperature properties of the base material. On the forced motions of antisymmetric cross-ply laminated plates Khdeir, A.A. and Reddy, J.N. International Journal of Mechanical Sciences Vol 31 No 7 (1989) pp 499-510 The transient response of an antisymmetric cross-ply rectangular plate under simply supported boundary conditions was studied when subjected to sinusoidally distributed transverse and blast (exponential) loading in the time domain. Dynamic solutions of the classical, first and third order laminate plate theories were obtained and the numerical
182
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solutions compared. The effects of anisotropy, the number of layers and transverse shear deformation are shown. The classical solution was shown to underestimate the transverse shear deflection. First and third order solutions yielded almost identical results. Prediction of variation of upper critical magnetic field of Nb2Sn superconducting composites as a function of applied stress at room temperature Ochiai, S. and Osamura, S. Acta Metallargica Vo137 No 9 (1989) pp 2539-2549 A model was proposed to predict the variation of upper critical magnetic field of bronze processed Nb2Sn superconducting composites as a function of applied stress on composites at room temperature. Calculations based upon the model developed agreed fairly well with those determined from experimental results. These results were attained on niobium filaments in a Cu-Sn alloy surrounded with a niobium barrier and then pure copper stabiliser. The upper critical magnetic field increased to a maximum with stress. The sensitivity of the ratio of the upper critical magnetic field, for the strained to the unstrained composite, increased with the level of the tin in bronze. A re-examination of the analysis of toughening in brittle-matrix composites Thouless, M.D. Acta Metallurgica Vo137 No 9 (1989) pp 2297-2304 The J-integral, as used for calculating the toughness of a brittle-fibre reinforced composite, was considered with respect to the role of interfacial friction. Upper and lower bounds were calculated for the toughness with the J-integral. These were determined by considering friction alone and a complete consideration of the losses associated with the mechanics of fibre failure respectively. A method was presented by which the J-integral could be combined with statistical models of fibre failure to incorporate the effects of fibre pull-out on the composites toughness. Stress fields in a composite material by means of a non-classical approach Ardic, E.S., Santare M.H. and Chou T.W. International Journal o f Engineering Sciences Vo127 No 11 (1989) pp 1397-1405 In this paper a method was developed to determine the separate stress field expressions for the materials in a two dimensional bimaterial composite body under elastic deformation. The model combines classical elasticity with nonlocal continuum mechanics and takes into account the effects of inhomogeneity and anisotropy. The solution for a condition of plane strain was compared with that obtained from classical models.
METAL MA TRICES The application of the Eshclby method of internal stress determination to short fibre metal matrix composites Withers, P.J., Stobbs, W.M. and Pendersen, O.B. Acta Metallurgica Vo137 No 11 (1989) pp 3061-3084
The prediction of mechanical properties of short fibre composites was theoretically dealt with using Elshelby's equivalent inclusion approach. The elastic, thermoelastic and plastic behaviour of this group of composites were predicted and compared with the experimentally determined results for the AI/SiC system. The role of relaxation phenomena in the development of internal stresses was determined. It was also confirmed that it was possible to understand the energctics and the resultant stress distribution between the two phases within the framework of the Elshelby model. Calculation of minimum pressure for liquid metal infiltration of a fibre array Nourbakhsh, S., Liang, F.L. and Margolin, H. Metallurgical Transactions A Vo120 A No 9 (1989) pp 1861-1866 Equations are derived in order to evaluate the effects of capillary forces on the pressure differential required for the infiltration of square and hexagonal arrays of parallel fibres by a liquid. Three different models are considered; i) unidirectional flow normal to the fibres, ii) bidirectional flow normal to the fibres and iii) three-dimensional flow. The lowest predicted infiltration pressure is derived from the three-dimensional model. Required pressure differentials for infiltration derived from models based on work of immersion are compared with the pressure differentials obtained from models based on capillary forces. Calculations of minimum pressure for liquid metal infiltration of a fibre array Nourbakhsh, S., Liang, F.L. and Margolin H. Metallurgical Transactions A Vol 20A No 9 (1989) pp 1861-1875 Equations have been derived which take into account the effect of capillary forces on the pressure differential required for liquid metal infiltration of a fibre array. Models were developed for both square and hexagonal arrays of fibres subjected to unidirectional, bidirectional and three-dimensional metal infiltration. The minimum pressure differential was calculated to be that for three dimensional infiltration of a hexagonal array. A comparison was made between models based on the work required for fibre immersion and the present model which is based on the work required to overcome the capillary forces. Crack bridging by uncracked ligaments during fatigue - crack growth in SiC reinforced aluminium alloy composites Shang, J.K. and Ritchie, R.O. Metallurgical Transactions A VoI 20 A No 5 pp 897-908 The role of crack tip shielding in enhancing the toughness of metal matrix composites is examined. Based on the study of crack bridging by uncracked ligaments in a powder metallurgy AI-Zn-Mg-Cu matrix alloy reinforced with 15-20 wt% SiC particulate, simple models are developed to predict the magnitude of crack tip shielding during fatigue crack growth. It is found that the production of uncracked ligaments is related to the fracture events occurring ahead of the crack-tip, such as the cracking of SiC particles, and that at higher crack growth rates bridging is seen to predominate since SiC particle fractures are significant only at higher stress intensity levels.