半固态Al-Zn-Mg-Cu合金的拉伸力学行为（英文）

Mechanical behavior of Al-Zn-Mg-Cu alloy under tension in semi-solid state

为了研究半固态成形过程中的热裂现象,在高温固态和半固态及不同应变速率对Al-Zn-Mg-Cu系挤压态7075铝合金进行拉伸试验。结果表明:随着液相率的升高,7075铝合金在拉伸过程中表现为3种变形机制。首先,合金表现为典型的塑性变形特征;随着温度升高,合金的变形行为由固相和液相共同决定,变形特点由塑性向脆性转变;液相率更高时,合金的变形行为完全由液相决定,并表现为明显的脆性变形特点。在应变速率分别为1×10^(-4)、1×10^(-3)和1×10^(-2) s^(-1)时,合金的脆性温度区间分别为515~526、519~550和540~580℃。此外,建立了关于拉伸行为的两个关键方程。

In order to study the hot fractures in relation to the semi-solid processing, the tensile tests of an extruded 7075 aluminum alloy which is based on Al?Zn?Mg?Cu system were carried out in the high temperature solid and semi-solid states at different strain rates. The results show that the tensile behavior can be divided into three regimes with increasing the liquid fraction. The alloy first behaves in a ductile character, and as the temperature increases, the fracture mechanism changes from ductile to brittle which is determined by both of liquid and solid, and lastly the fracture mechanism is brittle which is totally dominated by liquid. At strain rates of 1×10?4, 1×10?3 and 1×10?2 s?1, the brittle temperature ranges are 515?526, 519?550 and 540?580 °C, respectively. Two equations which are critical for tensile behavior are proposed.