AZ91镁合金的挤压和析出硬化行为(英文)

挤压比为4:1,将铸态AZ91镁合金分别在250,300和350℃下进行挤压,随后进行析出硬化处理(T6)。经过热挤压和析出硬化处理后,铸态AZ91镁合金中粗大的和偏析Mg17Al12析出相被细化并均匀分布在α-镁基体中。在不同的挤压温度下合金中发生了部分或全部动态再结晶。经挤压后,该合金的极限抗拉强度从铸态的190MPa增加到570MPa。AZ91镁合金的时效硬化特征与晶粒尺寸有关。在250、300和350℃下以4:1的挤压比挤压该合金后,获得峰值硬度的时效时间分别为35、30和20h。SEM观察到在AZ91基体中存在均匀细小的Mg17Al12析出相。

Extrusion and precipitation hardening behavior of AZ91 magnesium alloy

The as-cast AZ91 magnesium alloy was extruded at 250 °C, 300 °C and 350 °C, respectively with extrusion ratio of 4:1 followed by precipitation hardening treatment (T6). The coarse and segregated Mg₁₇Al₁₂ intermetallic precipitate in AZ91 magnesium alloy was refined and distributed uniformly in α-magnesium matrix by direct hot extrusion combined with precipitation hardening treatment. The dynamic recrystallization phenomenon, partial to full, was observed in this alloy with respect to the extrusion temperature. Ultimate tensile strength of this alloy is increased from 190 MPa (as cast) to 570 MPa after extrusion. The age hardening characteristics of AZ91 magnesium alloy is more dependent on the grain size. The peak hardnesses are obtained in the aging time of 35, 30 and 20 h for alloys extruded with ratio of 4:1 at three different temperatures. Uniform and fine precipitates of Mg₁₇Al₁₂ in AZ91 Mg matrix were confirmed by scanning electron microscope (SEM).