| Platinum group engineering materials(platinum,platinum alloys,etc.)have good mechanical properties and chemical inertness both at room temperature and at high temperature.It was often processed into blender,bushing and crucible to be used in glass,ceramic and chemical fields.In the manufacturing process of glass fiber and flat panel display glass,only the platinum group engineering materials can meet the requirements of stable service at high temperature.The grain of normal platinum and platinum alloy will grow up bamboo shaped after used in the long time at high temperature,which leads to deterioration of mechanical properties.The alloy has defects,such as deformation and fracture.The properties of platinum alloy can be improved by the methods of grain boundary strengthening,solid solution strengthening,deformation strengthening,second-phase strengthening and dispersion strengthening.Among them,oxide dispersion strengthened Pt-Rh alloy is one of the most highly respected platinum engineering materials in the industry.In this work,the deficiency of the performance of Pt-Rh alloy was studied,which has been used widely in the manufacture of glass fiber and flat panel display glass.This microstructure and mechanical properties were investigated at high and low temperature.The main work and results are as follows:(1)A series of sheet samples of Pt-Rh-Zr-Y alloy with the content of Zr from 0 to 0.3wt% and the content of Y from 0 to 0.05wt% were prepared by alloy melting,milling process,internal oxidation,powder forming,rolling and heat treatment.(2)The microstructure and phase composition of the alloy were observed and analyzed by means of metallographic microscope,electron microscope and X-ray diffraction(XRD).The results show that the microstructure of Pt-Rh-Zr-Y platinum alloy presents fibrous textures;the phase composition of alloy mainly is platinum-rhodium solid solution matrix phase and reinforcement phase,reinforcement phase mainly included oxides dispersed phase and intermetallic precipitates,which dispersed oxide phases are oxide particles of Y2O3,ZrO2 and Zr-Y-O,intermetallic compound as precipitation phase is mainly of Pt3 Y,Rh2Y and Rh3Zr;The content of Zr increased from 0 to 0.3wt%,the width of Pt-20Rh-xZr-0.015 Y alloy grain firstly increased and then decreased,while the number of recrystallized grain has no obvious change trend;The Pt-20Rh-0.1Zr-0.015 Y alloy has the largest grain width and the least recrystallized grains.;The content of Y increased from 0 to 0.050wt%,there was no obvious change in the grain size and the number of recrystallization grain of Pt-20Rh-0.1Zr-xY alloy.The Pt-20Rh-0.1Zr-0.015 Y alloy has the largest grain width and the least recrystallized grain.(3)The mechanical properties of Pt-20Rh-xZr-0.015 Y platinum alloy were tested and analyzed at room temperature and high temperature.The results showed that: Compared with Pt-20 Rh alloy,the strength of Pt-20Rh-xZr-0.015 Y alloy was greatly improved and the elongation is decreased obviously;when the content of Zr increased from 0 to 0.3wt%,the yield strength and tensile strength of Pt-20Rh-xZr-0.015 Y alloy increased continuously at room temperature,while the extensibility decreased continuously;the yield strength and tensile strength of Pt-20Rh-xZr-0.015 Y alloy increase continuously at high temperature,while the elongation decreases;the highest yield strength and tensile strength of Pt-20Rh-0.3Zr-0.015 Y alloy at room temperature were separate 261 MPa and 557 MPa,which were increased by 136.8% and 47.6% compared to Pt-20 Rh alloy respectively;for high temperature the highest yield strength and tensile strength were separate 122 MPa and 149 MPa,which were increased by 127.3% and 30.2%,respectively,compared with that of Pt-20 Rh alloy.The room temperature elongation of Pt-20Rh-0.3Zr-0.015 Y alloy was 48.6%,while the elongation is about 22.6% at high temperature.(4)The mechanical properties of Pt-20Rh-0.1Zr-xY platinum alloy were tested and analyzed at room temperature and high temperature.The results showed that: Compared with Pt-20 Rh alloy,the strength of Pt-20Rh-0.1Zr-xY alloy was greatly improved and the elongation was decreased;when the content of Y increased from 0 to 0.05w0t%,The yield strength and tensile strength of the alloy showed a trend of increasing first and then decreasing at room temperature,while the elongation rate of the alloy was in the amplitude fluctuation with the small variation;when at high temperature,the yield strength,tensile strength and elongation of the alloy showed amplitude fluctuation with the small change;the highest yield strength and tensile strength of Pt-20Rh-0.1Zr-xY alloy at room temperature were separate 250 MPa and 492 MPa,which were increased by 127.3% and 30.2% compared to Pt-20 Rh alloy respectively;for high temperature the highest yield strength and tensile strength were separate 97 MPa and 134 MPa,which were increased by 76.4% and 59.5%,respectively,compared with that of Pt-20 Rh alloy;The room temperature elongation rate of Pt-20Rh-0.1Zr-0.015 Y alloy was 47.7%,which was the highest extensibility in Pt-20Rh-0.1Zr-xY alloy;the elongation of alloy at high temperature was 27%.(5)The relationship between structure and properties of alloy and alloy strengthening mechanism was discussed.The results showed that: the microstructure of Pt-Rh-Zr-Y platinum alloy presents fibrous textures at room temperature and high temperature;the grain has a high ratio of length to width,which helps to maintain a high strength alloy at room temperature and high temperature;the Strengthening mechanism of Pt-Rh-Zr-Y platinum alloy includes a variety of enhancement patterns,which includes possible mechanisms of solution strengthening,precipitation strengthening,and a variety of oxide dispersion strengthening.Rhodium is dissolved in the platinum to strengthen matrix.The oxide particles and intermetallic compounds have the function of suppression of dislocation movement,grain boundary migration and grain growth hindrance,which is dispersed at grain boundaries. |
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