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Composites
~~~~~~~~~~~~i.iterature recognition function with a finite set of known classes; therefore. not every potential shape will fit an existing class. Shapes initially unrecognized arc classified by relaxation ofclass limits or by creation of a new class. A measure of confidence in the classification is used to affect the rules applied in design refinement. and to signal the designer that process simulation using FEl\lshould be applied to the resultant design. FINITE ELEMENT SIMULATION OF COLD DIE Cm.WACTION LEADING TO SINTERED PART DIMENSION CONTROL J I' Bandstra, \V L Otto (Metalworking Technology. Inc.) Experiments were run on cylindrical specimens to evaluate the analytical results. Graphical results of dimensional changes. shrinkageand concavity. are presented which compare the analytical and experimental results.
ALUMINIUM
In order to improve the properties achieved by means of conventional degassing, a vacuum degassing process and flushing, with argon or nitrogen was used. The research concerned rapidly solidified PM AI-20Si-3Cu-1Mg canned powders degassed arid flushed at temperatures of 200, 300 and 400C. The can with the decontaminated powder was compressed to full density and extruded at 375C with an extrusion ratio of 1:20. The extruded specimens were heat treated. The heat treated samples were annealed at the subsequent test temperatures of 100,200, 300 and 400Cfor 100 hours. The products were subjected to tensile test at roomand elevated temperatures of 100,200,300 and 400 C at a strain rate of 0.5 x 1O.2s·l • The microstructures were investigated by means oflight microscopy. Researchshowed that degassing of the alloy with modified conditions gives improved properties in comparison to those products conventionally degassed. THE EFFECT OF POWDER METALLURGY PROCESSING ON TIlE MICROSTRUCTURE AND FATIGUE PROPERTIES OF AN ALUMINUM-LITIIIUM ALLOY T S Srivatsan, E J Lavernia (University of Akron)
A SIMPLE, LADORATORY MEANS TOPRODUCE TOUGH ALUMINUM SHEET FROMPOWDER
a RSingleton (SingletonTechnology. Inc) and D M Royster. et al, (NASA Langley Research Centre) This paper describes laboratory equipment and associated procedures which can be used to produce tough PMaluminum sheet. The processing of a 0.9% Zr aluminum alloy powder is used as an example. Fully hardened sheet product is evaluated in terms of mechanical properties and microstructure. Vacuum hot pressing used to consolidate the aluminum powder is described. The 0.9% Zr aluminum sheet produced was both strong and tough. The microstructure was well refined with grains or subgrains of 1-2 11m POWDER FORGING OF RAPIDLY SOLIDIFIED ALUMINUM ALLOY POWDERS AND MECHANICAL PROPERTIES OFTIIEIR FORGED PARTS M Otsuki, et al (Mitsubishi Metal Corporation) PM forging of rapidly solidified aluminum alloy powders was investigated. The results of this study are summarized as follows: Several PM forging . processes for Al·25%Si-3%CU.1%Mg-10/0Fe alloy powders for production of wear resistance parts showed that mechanical properties of this alloy produced by the rigid die hot coining followed by the rigid die hot forging arc as good as those of extruded parts made fromalloy powders ofthe same composition. Forging of AI-9 %Fe-1.50/0V-I %Zr alloy powders for preparation of heat resistance parts were investigated. which showed that their tensile strength and elongation arc strongly affected by the reduction ratio and large reduction ratio is required to obtain good tensile properties. PROPERTIES IMPROVEMENT OF RAPIDLY SOLIDIFIED PM AI·20Si·X ALLOYS BYMEANS OF MODIFIED DEGASSING J L Estrada-Hacn, J Duszczyk (Delft University of Technology)
MPR July/August 1990
A spray deposited AI-4Li-1Mg-0.2Zr-0.5Ge alloy was extruded into rectangular bars 12.5 mm in thickness. Microstructural features of the material were characterised in the solution heat treated and aged condition. Tensile specimens were deformed to failure and fractographic investigation conducted. The cyclic stress response and fatigue properties of the alloy were evaluated over a range of plastic strain giving lives of less than 104 cycles. Topography of the fatigue fracture surfaces of specimens cycled to failure at high and low strain amplitudes was also conducted. The kinetics governing the fatigue process will be discussed in the light of dislocation-precipitate interaction, deformation and fracture process.
COMPOSITES
Review
TRIBOLOGICAL PROPERTIES OFPM ALUMINUM ALLOY MATRIX COMPOSITES A R Jokinen, I' G Andersson (Technical Research Centre of Finland) Tribological properties of hot-extruded silicon carbide particulate reinforced aluminum PM alloy 6061 arc studied. The materials were examined in unlubricated and lubricated pin-on- disc tests and in abrasion tests. Microstructural analyseswerealso used for evaluating the tribological behaviour. Addition of silicon carbide slightly decreased the wear rate of the alloy during the unlubricated pin-on-disktests. Deformationofthe sliding contact region occurred on the aluminum pins, but to a smaller extent on pins reinforced with larger particulates. Materialstransfer fromthe pins to their steel counterfacos was observed, this indicating strong adhesion. In the abrasion tests, wear rates decreased with increasing silicon carbide content. Silicon carbide particulates decreased the wear rates of the composites up to 45% compared to the conventionally produced matrix alloy.
WEAR RESISTANT TITANIUM·TITANIUM CARBIDE COMPOSITES FOR LIGHTIVEIGIIT APPLICATIONS J M Panchal, T Vela (Alloy Technology International Inc) This paper describes the use of particulate composite technologies to develop a metal rr:atrix composite by conventional PM techniques. Reinforcement ofa titanium matrix with superhard ceramic particles of titanium carbide (TiC), significantly improves its hardness and wear resistance. Effects of varying levels of TiC on the sinterability and microstructure of titanium arc investigated. Addition of TiC enhances the sinterability of titanium. Compositions with TiC concentrations in excess of 25 vol.% result in the formation of a network of carbides in the microstructure. DUPLEX PM TURNING TOOLS
AGING CHARACTERISTICS AND MECHANICAL PROPERTIES OF SILICON CARBIDE WHISKER REINFORCED ALUMINUM MATRIX COMPOSITES R B Bhagat, et al (The Pennsylvania State University) AgingcharacteristicsofSiCfibre (VfO.2)re-inforced 6061 Al composites were stud ied using solution treatment at 530 and aging at 150 and 200C for 5 mins to 96 hrs. Microhardness peaks of148 and 138 for 150C(18 hrs) and 20C [Ihr] observed. values) those for wrought 6061-T6 AI alloy. Deduced that presence of SiC alters aging characteristics.
M N H Ahmed, et al (El-Azhar University. Cairo) This paper describes attempts to design a cutting toolconsisting ofa hard cutting tip bonded to a stiff, lower cost. holder and intended to be produced in one operation. Stress analysis, mechanical and physical properties and changes in processing are used to design the tool by mathematical modelling and experiment. PREPARATION AND PROPERTIES OF HYBRID ANTIFRICTION BEARINGS STEEL-CERAMICS USINGHOT ISOSTATIC PRESSING AND HOT PRESSING
TIIEIU.L\L STABILITY OF TIlE DISPERSION STRENGTIIENED AI-AI 4C3
A Havalda, ct al (Slovak Technical University of Bratislava)
M Bestcrci, et al (SlovakAcademy of Sciences)
Hybrid roller bearingswere made usi.ng l\~2I1SS for the inner and outer rincs and ccrarrnc, SIN, for the rollers. Cage slip depe~dence on rotati?nal speed was observed, comparison was made WIt? all steel bearings. The hybrid bearings gave Improved performance in special applications.
Thermal stability of two series of dispersion strengthened AI- AI4C3 systems with 8 vol% AI4C3 were analysed by examination of the mechanical properties and substructure changes.
575
ALUMINIUM
In order to improve the properties achieved by means of conventional degassing, a vacuum degassing process and flushing, with argon or nitrogen was used. The research concerned rapidly solidified PM AI-20Si-3Cu-1Mg canned powders degassed arid flushed at temperatures of 200, 300 and 400C. The can with the decontaminated powder was compressed to full density and extruded at 375C with an extrusion ratio of 1:20. The extruded specimens were heat treated. The heat treated samples were annealed at the subsequent test temperatures of 100,200, 300 and 400Cfor 100 hours. The products were subjected to tensile test at roomand elevated temperatures of 100,200,300 and 400 C at a strain rate of 0.5 x 1O.2s·l • The microstructures were investigated by means oflight microscopy. Researchshowed that degassing of the alloy with modified conditions gives improved properties in comparison to those products conventionally degassed. THE EFFECT OF POWDER METALLURGY PROCESSING ON TIlE MICROSTRUCTURE AND FATIGUE PROPERTIES OF AN ALUMINUM-LITIIIUM ALLOY T S Srivatsan, E J Lavernia (University of Akron)
A SIMPLE, LADORATORY MEANS TOPRODUCE TOUGH ALUMINUM SHEET FROMPOWDER
a RSingleton (SingletonTechnology. Inc) and D M Royster. et al, (NASA Langley Research Centre) This paper describes laboratory equipment and associated procedures which can be used to produce tough PMaluminum sheet. The processing of a 0.9% Zr aluminum alloy powder is used as an example. Fully hardened sheet product is evaluated in terms of mechanical properties and microstructure. Vacuum hot pressing used to consolidate the aluminum powder is described. The 0.9% Zr aluminum sheet produced was both strong and tough. The microstructure was well refined with grains or subgrains of 1-2 11m POWDER FORGING OF RAPIDLY SOLIDIFIED ALUMINUM ALLOY POWDERS AND MECHANICAL PROPERTIES OFTIIEIR FORGED PARTS M Otsuki, et al (Mitsubishi Metal Corporation) PM forging of rapidly solidified aluminum alloy powders was investigated. The results of this study are summarized as follows: Several PM forging . processes for Al·25%Si-3%CU.1%Mg-10/0Fe alloy powders for production of wear resistance parts showed that mechanical properties of this alloy produced by the rigid die hot coining followed by the rigid die hot forging arc as good as those of extruded parts made fromalloy powders ofthe same composition. Forging of AI-9 %Fe-1.50/0V-I %Zr alloy powders for preparation of heat resistance parts were investigated. which showed that their tensile strength and elongation arc strongly affected by the reduction ratio and large reduction ratio is required to obtain good tensile properties. PROPERTIES IMPROVEMENT OF RAPIDLY SOLIDIFIED PM AI·20Si·X ALLOYS BYMEANS OF MODIFIED DEGASSING J L Estrada-Hacn, J Duszczyk (Delft University of Technology)
MPR July/August 1990
A spray deposited AI-4Li-1Mg-0.2Zr-0.5Ge alloy was extruded into rectangular bars 12.5 mm in thickness. Microstructural features of the material were characterised in the solution heat treated and aged condition. Tensile specimens were deformed to failure and fractographic investigation conducted. The cyclic stress response and fatigue properties of the alloy were evaluated over a range of plastic strain giving lives of less than 104 cycles. Topography of the fatigue fracture surfaces of specimens cycled to failure at high and low strain amplitudes was also conducted. The kinetics governing the fatigue process will be discussed in the light of dislocation-precipitate interaction, deformation and fracture process.
COMPOSITES
Review
TRIBOLOGICAL PROPERTIES OFPM ALUMINUM ALLOY MATRIX COMPOSITES A R Jokinen, I' G Andersson (Technical Research Centre of Finland) Tribological properties of hot-extruded silicon carbide particulate reinforced aluminum PM alloy 6061 arc studied. The materials were examined in unlubricated and lubricated pin-on- disc tests and in abrasion tests. Microstructural analyseswerealso used for evaluating the tribological behaviour. Addition of silicon carbide slightly decreased the wear rate of the alloy during the unlubricated pin-on-disktests. Deformationofthe sliding contact region occurred on the aluminum pins, but to a smaller extent on pins reinforced with larger particulates. Materialstransfer fromthe pins to their steel counterfacos was observed, this indicating strong adhesion. In the abrasion tests, wear rates decreased with increasing silicon carbide content. Silicon carbide particulates decreased the wear rates of the composites up to 45% compared to the conventionally produced matrix alloy.
WEAR RESISTANT TITANIUM·TITANIUM CARBIDE COMPOSITES FOR LIGHTIVEIGIIT APPLICATIONS J M Panchal, T Vela (Alloy Technology International Inc) This paper describes the use of particulate composite technologies to develop a metal rr:atrix composite by conventional PM techniques. Reinforcement ofa titanium matrix with superhard ceramic particles of titanium carbide (TiC), significantly improves its hardness and wear resistance. Effects of varying levels of TiC on the sinterability and microstructure of titanium arc investigated. Addition of TiC enhances the sinterability of titanium. Compositions with TiC concentrations in excess of 25 vol.% result in the formation of a network of carbides in the microstructure. DUPLEX PM TURNING TOOLS
AGING CHARACTERISTICS AND MECHANICAL PROPERTIES OF SILICON CARBIDE WHISKER REINFORCED ALUMINUM MATRIX COMPOSITES R B Bhagat, et al (The Pennsylvania State University) AgingcharacteristicsofSiCfibre (VfO.2)re-inforced 6061 Al composites were stud ied using solution treatment at 530 and aging at 150 and 200C for 5 mins to 96 hrs. Microhardness peaks of148 and 138 for 150C(18 hrs) and 20C [Ihr] observed. values) those for wrought 6061-T6 AI alloy. Deduced that presence of SiC alters aging characteristics.
M N H Ahmed, et al (El-Azhar University. Cairo) This paper describes attempts to design a cutting toolconsisting ofa hard cutting tip bonded to a stiff, lower cost. holder and intended to be produced in one operation. Stress analysis, mechanical and physical properties and changes in processing are used to design the tool by mathematical modelling and experiment. PREPARATION AND PROPERTIES OF HYBRID ANTIFRICTION BEARINGS STEEL-CERAMICS USINGHOT ISOSTATIC PRESSING AND HOT PRESSING
TIIEIU.L\L STABILITY OF TIlE DISPERSION STRENGTIIENED AI-AI 4C3
A Havalda, ct al (Slovak Technical University of Bratislava)
M Bestcrci, et al (SlovakAcademy of Sciences)
Hybrid roller bearingswere made usi.ng l\~2I1SS for the inner and outer rincs and ccrarrnc, SIN, for the rollers. Cage slip depe~dence on rotati?nal speed was observed, comparison was made WIt? all steel bearings. The hybrid bearings gave Improved performance in special applications.
Thermal stability of two series of dispersion strengthened AI- AI4C3 systems with 8 vol% AI4C3 were analysed by examination of the mechanical properties and substructure changes.
575