Effect of Sintering Temperature on Microstructure,Properties,and Impurity Content of Niobium-Tungsten Alloy Bars AITranslate

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Chinese Library Classification Number:TG146.416[一般工业技术]

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The niobium-tungsten alloy bars prepared by steel mold cold pressing were sintered at high tem-peratures of 1700℃,1800℃,1900℃,and 2000℃.The effects of sintering temperature on the micro-structure,properties,and impurity content of the alloy bars were investigated using a infrared oxygen/ni-trogen analyzer,infrared carbon/sulfur analyzer,metallographic microscope,glow discharge mass spec-trometer,Archimedes drainage method,and photoelectric deflection tester.The results indicate that the densification degree,shrinkage rate,and deflection of the alloy bars increase progressively with elevated sintering temperature.The relative density of the alloy bars sintered at 1900℃and 2000℃both exceeds 95%.With the increase of sintering temperature,the elongated fibrous microstructure in the alloy bars gradually diminishes and eventually disappears,while the grains progressively evolve into an equiaxed mor-phology,accompanied by a continuous reduction in impurity content.The alloy bars sintered at 1900℃have oxygen and carbon contents of 0.054%and 0.058%,respectively,demonstrating significant removal of carbon and oxygen impurities.When the sintering temperature reaches 2000℃,over-sintering induces partial melting of grain boundaries,resulting in excessive densification of the alloy bars due to extreme shrinkage rate.This hinders subsequent electron beam melting purification.Additionally,the alloy bars ex-hibit excessive deflection and reduced straightness,making them unsuitable for refining bundle.The opti-mal sintering temperature for niobium-tungsten alloy bars is determined to be 1900℃based on compre-hensive analysis.