(哈爾濱工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，
哈爾濱 150001)
摘 要: 以SIMA法制備的非枝晶LC4合金為例，進(jìn)行壓縮試驗(yàn)，測(cè)出了應(yīng)變速率、變形溫度及保溫時(shí)間不同時(shí)的屈服應(yīng)力。結(jié)果表明：當(dāng)應(yīng)變速率相同時(shí)，在固態(tài)區(qū)，屈服應(yīng)力隨著變形溫度的增加稍有減小；而在半固態(tài)區(qū)，屈服應(yīng)力隨著變形溫度的提高明顯減小，且在共晶點(diǎn)附近急劇下降。屈服應(yīng)力隨著保溫時(shí)間增加而略有減小的主要原因是由于隨著保溫時(shí)間的增加，晶粒的尺寸、球形化程度、固相晶粒間的結(jié)合程度及晶粒內(nèi)俘獲的液體不同所致。當(dāng)變形溫度及保溫時(shí)間相同時(shí)，隨著應(yīng)變速率的升高，屈服應(yīng)力明顯增加。通過(guò)分析不同變形溫度及保溫時(shí)間的材料顯微組織進(jìn)化規(guī)律，闡明了屈服應(yīng)力與顯微組織之間的內(nèi)在聯(lián)系。
關(guān)鍵字: 屈服應(yīng)力；顯微結(jié)構(gòu); 變形溫度; 保溫時(shí)間; 應(yīng)變速率
semi-solid state
（School of Materials Science and Engineering，
Harbin Institute of Technology，Harbin 150001,China）
Abstract:Extensive compression experiments were conducted to measure yield stress under different strain rates，deformation temperatures and holding times.Non-dendritic LC4 alloy fabricated by SIMA method was used.The results of yield stress measurements in a constant strain rate were presented.Yield stress value decreases slightly with the increasing of temperature in solid state，whereas yield stress value decreases dramatically with the increasing of temperature in semi-solid state.A sharp drop of yield stress was found to occur at eutectic point.Grain size，spheroidization，cohesion between solid grains and entrapped liquid inside grains are different with the increasing of holding time，which results in a decrease of yield stress. The results of yield stress measurements at a constant temperature and holding time were also presented. The yield stress value increases dramatically with the increasing of strain rate.In addition，microstructure evolutions at different temperatures and holding time are analyzed.Inherent relationship between yield stress and microstructure is clarified.
Key words: yield stress; microstructure; deformation temperature; holding time; strain rate
