Powder injection moulding of Ti-47.5Al-2.5V-1.0Cr
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摘要: 以Ti-47.5Al-2.5V-1.0Cr(原子分數,%)氣霧化預合金粉末為原料,采用粉末注射成形工藝制備了Ti舢合金材料,研究了該TiAl合金脫脂工藝對脫脂坯碳氧殘留量和組織的影響規律及燒結工藝對燒結體顯微組織、密度和壓縮性能的影響規律.結果表明:在脫脂溫度600℃、保溫時間為1h和真空脫脂氣氛條件下脫除坯體中剩余粘結劑,坯體中殘余碳氧含量(質量分數)分別為0.059%和0.12%;脫脂溫度從600℃升到1000℃,粉末由枝狀組織轉變為近γ組織;燒結溫度在1410~1450℃,保溫時間在1h以內,燒結體可以快速致密化;在1450℃保溫30min,燒結體相對密度可以達到95%,燒結體的抗壓強度為2105MPa,壓縮率達到30.9%,接近鑄態合金力學性能;隨燒結溫度升高,燒結體中的γ相逐漸減少,組織由近片層組織逐漸轉變為全片層組織.Abstract: The injection molding of Ti-47.5Al-2.5V-1.0Cr gas-atomized pre-alloy powders was carried out. The effects of debinding on the contents of residual carbon and oxygen and the microstructure of brown parts and the influences of sintering temperature on the sintered microstructure, density and compressive property of the alloy were investigated. The results showed that the mass fractions of residual carbon and oxygen were 0. 059% and 0.12% respectively under the condition of the thermal debinding temperature of 60012, the holding time of 1 h and vacuum atmosphere. The microstructure was changed from dentritic to nearamma (NG) microstructure when the sintering temperature increased from 600℃ to 1000℃. The specimens densified rapidly at 1410-1450 12 for 1 h. When the vacuum slntering was employed, a near full density of 95% was obtained at 1450℃ after 30min holding, and the compression strength and compression ratio were 2105 MPa and 30.9% respectively, which are near to those of the cast alloy. With the sintering temperature increasing, the amount of y phase decreases gradually. The microstructure was changed from near a lamelar microstructure to a fully lamellar microstructure when the sintering temperature increased from 1410 IE to 1 450℃.
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Key words:
- TiAl alloy /
- powder injection molding /
- sintering /
- debinding
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