稀土对ZA27合金压蠕变的影响

Effect of Rare Earths on Compressive Creep Behavior of ZA27 Alloy

采用自制的实验装置研究了稀土 (Ce≥ 45 % )对ZA2 7合金在常温及高温时的压蠕变行为的影响。研究表明 ,在所试验的温度为 2 0℃～ 160℃和压应力为 5 0MPa～ 13 7 5MPa的范围内 ,加稀土的ZA2 7—RE合金和未加稀土的ZA2 7合金的压蠕变量均随着温度和应力的升高而增大 ,ZA2 7—RE合金的压蠕变速率小于ZA2 7合金的压蠕变速率。加入稀土后 ,合金在压蠕变过程中的负蠕变量及出现负蠕变的温度和应力范围增大。两种合金的稳态蠕变速率均符合于半经验公式ε 's=Aσnexp( -Qa RT)。但在不同的温度 ,ZA2 7—RE合金的应力指数平均值n( 4 66)和表观激活能平均值Qa( 70 45KJmol- 1 )均大于ZA2 7合金的应力指数平均值n( 3 87)和表观激活能平均值Qa( 68 2 2KJmol- 1 ) ,而合金的材料结构常数A为 4 82× 10 - 5,低于ZA2 7合金的材料结构常数A( 0 0 0 2 )。

The effect of rare earths on compressive creep behavior of an as-cast ZA27 alloy was investigated at room and high temperature in the range of 20℃～160℃ and different compressive stress in the range of 50MPa～137.5MPa with a special apparatus.Results obtained show that compressive creep deformations of ZA27—RE alloy and ZA27 alloy increased with temperature and compressive stress,and the steady creep rate of ZA27—RE alloy was lower than that of ZA27 alloy.The negative creep deformations increased after adding some rare earths to ZA27 alloy,and the ranges of temperature and stress at which the negative creep occurred extended.The steady creep rates of ZA27—RE alloy and ZA27 alloy could obeyed an empirical equation ε ' s=Aσ nexp(-Q a/RT).Compared with ZA27 alloy,the average exponent n and the average appearance activation energy Q a of ZA27—RE alloy were greater.However,materials constant A of ZA27—RE alloy and ZA27 alloy was 4.82×10 -5 and 0.002,respectively.It was considered that the steady creep rates in both ZA27—RE and ZA27 were controlled by lattice diffusion in Zinc and by a dislocation limb.