( 東南大學(xué) 材料科學(xué)與工程系，南京 210096)
摘 要: 研究了控制熔體結(jié)晶法制備的半固態(tài)ZL101合金的壓縮變形行為以及顯微組織的變化。 結(jié)果表明： 在液固相區(qū)二次加熱并保溫足夠時間后， 該合金的球狀固相仍保持半固態(tài)加工要求的適當(dāng)尺寸， 575 ℃和582 ℃壓縮變形時， 半固態(tài)漿料具有穩(wěn)定觸變流動變形特征， 即應(yīng)力隨應(yīng)變增大而緩慢下降， 其應(yīng)力水平較接近固相線的高溫(550 ℃)塑性變形應(yīng)力低得多； 枝晶組織和高變形速率提高半固態(tài)合金的變形應(yīng)力，并使應(yīng)力隨應(yīng)變增大而單調(diào)提高； 大變形后， 圓柱試樣中心和邊緣區(qū)域存在球狀初生α相變形程度的不同。 半固態(tài)變形中， 變形機(jī)理從以阻尼液相流動為主變?yōu)橐怨滔囝w粒塑性變形為主。
關(guān)鍵字: 半固態(tài)合金；壓縮變形； 真應(yīng)力； 真應(yīng)變； 顯微組織
microstructure of semi-solid Al-Si alloy
（Department of Materials Science and Engineering, Southeast University,Nanjing 210096, China）
Abstract: Compression experiments were carried out to investigate deformation behavior and microstructure of semi-solid ZL101 alloy fabricated by controlled crystallization technique. The results show that the alloy has reasonable size of globular solid required for semi-solid processing after reheating to temperatures in liquid-solid range and sufficient holding time. The semi-solid slurry has stable thixotropic flow deformation behavior under compressing at 575 ℃ and 582 ℃, i.e. stress decreasing gradually with strain increasing, and in this case, the deformation stress is much lower than that of the specimen deformed at temperature (550 ℃) close to solidus. Both dendritic structure and high strain rate enhance the deformation stress of the semi-solid alloy, and enable the stress to increase with strain continuously. The deformation degree difference of globular primary α phase appears at center and edge areas in the cylinder specimen after large deformation. The deformation mechanism of damped liquid flow domination becomes solid particle plastic deformation domination during deformation in semi-solid state.
Key words: semi-solid alloy; compression deformation; true stress; true strain; microstructure
