摘要
研究Mg-9Gd-3Y-0.3Zr合金在不同温度（200-300℃）和应力（30-110MPa）条件下的蠕变行为,利用金相显微镜、透射电镜等分析蠕变过程中合金组织的演变。结果表明：温度较低时（200-250℃）,蠕变曲线分为瞬时和稳态蠕变两部分,利用Arrhenius公式计算出合金的平均应力指数n=2,由此判断蠕变机制是晶界滑移机制,平均蠕变激活能Q=85.6kJ/mol;当温度为300℃时,合金经过短暂的瞬时蠕变和稳态蠕变阶段后,很快进入断裂阶段。n=4.2,蠕变机制为位错攀移机制,Q=145.5 kJ/mol。在温度较低时,稀土元素所形成的析出相β￠相阻碍位错的运动,从而提高合金的抗蠕变能力;随蠕变温度升高,析出相转变为β相,在晶界处聚集长大,使晶界处易产生应力集中,促使孔洞的形成,导致合金发生蠕变断裂。
The creep behavior of Mg-9Gd-3Y-0.3Zr alloy was studied by the RC-950 creep endurance testing machine under different temperatures（200-300 ℃） and stresses（30-110 MPa）. The microstructure evolvement during the creep procedure was investigated by TEM（transmission electron microscopy） and OM（optical microscope）. The results show that when temperature is in the range of 200-250 ℃, the creep curves can be divided into two stages： transient creep stage and steady creep stage; The average stress exponent（n） of the alloy calculated through Arrhenius formula is 2, from which the grain boundary creep mechanism can be concluded. The average creep activation energy（Q） is 85.6 kJ/mol.When temperature is 300 ℃, after a transient instantaneous creep and a steady creep stages, the alloy enters rupture creep stage soon. When n=4.2, the creep mechanism is climb of dislocation and Q=145.5 kJ/mol. When the temperature is lower, the precipitation phase β′ can improve the creep resistance by blocking dislocation movement. With increasing temperature, the precipitation transforms to β phase, which aggregates and grows in the grain boundary, results in the stress concentration and pores formation, and ultimately leads to the rupture of the alloy.
出处
《粉末冶金材料科学与工程》
EI
北大核心
2014年第4期576-583,共8页
Materials Science and Engineering of Powder Metallurgy
基金
五矿湖南有色基金项目(YSZN2013CL01)
国家科技支撑计划项目(2011BAE09B03)
