The Effect Of Recasting On Composition And Microstructure Of The Non-Nickel-based Ceramic Alloys

Objective: To study the effects of recasting on Composition and Microstructure ofthe non-nickel-based ceramic alloys.Methods: The non-nickel-based ceramic alloys were recast for1-3times under thecircumstance of vacuum compressive casting with argon. Before being recast again,the non-nickel-based ceramic alloys should be treated with “the most appropriate wayto treat metal alloys before recast.(1) Detected the four kinds of ceramic alloyschemical composition by energy dispersive spectrometer (EDX);(2) According toGB/T13298-91standards, respectively, grinding, polishing, etching on the four kindsof ceramic alloy, detected the microstructure of the alloy by a scanning electronmicroscopy(SEM);(3) Detected the phase structure of the four kinds of ceramic alloyby X-ray diffraction(XRD)Results:(1) After casting1-3times, there presented no statistical change on thecontent of chemical composition of Co-Cr ceramic alloys except the element of Co,W,Mo,Ga. Compared with the first generation samples of Co-Cr ceramic alloys, thesecond one was statistical increase in the content of Co element, the third one wasstatistical increase in the content of Ga element, the second and the third ones werestatistical decrease in the content of W,Mo element; After casting1-3times, therepresented no significant change on the content of chemical composition of Ti ceramicalloys; After casting1-3times, there presented no statistical change on the content ofchemical composition of Pd-base ceramic alloys except the element of Cu,Pd,Ga.Compared with the first generation samples of Pd-base ceramic alloys, the second onewas statistical increase in the content of Cu element, and decrease in the content of Pdelement, the third one was decrease in the content of Ga element; After casting1-3times, there presented no significant change on the content of chemical compositionof Au-Pt ceramic alloys.(2)The microstructure of the original Co-Cr ceramic alloy was austenite and intermetallic compound, after casting1-3times, the microstructureshowed grain growth, grain matrix increase, the intermatallic compound in the grainboundary increase; The microstructure of the original Ti ceramic alloy was compoundof α-phase lamellas, after casting1-3times, the microstructure showed grain growth.The second generation samples appeared shaft tendency,and the third ones wascompound ofα-phase and β-phase; The microstructure of the original Pd-baseceramic alloy was austenite with equiaxed grains, after casting1-3times, themicrostructure showed grain growth; The microstructure of the original Au-Pt ceramicalloy was austenite, after casting1-3times, there presented no statistical change onthe microstructure.(3)After casting1-3times, there presented no significant differenceof phase structure of Ti, Pd-base, Au-Pt ceramic alloy; phase structure of the secondgeneration samples of Co-Cr ceramic alloy occured FCC to HCP.Conclusion: Under the circumstance of vacuum compressive casting with argon,(1) Chemical content of the element of W,Mo in Co-Cr ceramic alloys and of theelement of Pd,Ga in Pd-base ceramic alloys gradually decreased with the increase inthe number of recast; there presented no significant change on the content of chemicalcomposition of Ti ceramic alloys and Au-Pt ceramic alloys.(2)the microstructure ofnon-nickel-based ceramic alloys showed grain growth and shrinkage porosity increasewith the number of recast times; Ti ceramic alloys occurred αâ†'βphase.(3) Afterrecasting1-3times, Co-Cr alloy occurs fccâ†'hcp phase transition, while there wasno significant difference of phase structure between original CP-TI,Pd-Cu,Au-Pt alloyand each generation castings.