金属铍静态再结晶行为

Static recrystallization behaviors of the metal beryllium

摘要:

通过热压缩和真空退火实验系统研究了金属铍低温形变(应变温度350 ℃,应变速率10_^-3 s_^-1,应变量30%)后在680 ℃至880 ℃温度区间退火组织演变规律。结果表明：金属铍具有独特的静态再结晶行为,再结晶晶粒首先在10 2}<10 >拉伸孪晶界处形核,机理为应变诱导的孪晶界弓出形核。晶界“弓出”形核落后于孪晶界“弓出”形核的原因是BeO杂质对原始晶粒晶界钉扎,阻碍了其界面的迁移。孪晶界和原始晶粒晶界“弓出”形核是金属铍主要的形核方式,晶内直接形核和杂质处形核是其次要的形核方式。低温形变铍在680 ℃至880 ℃内退火均能够获得晶粒细化的完全再结晶组织,且没有再结晶织构形成。金属铍的再结晶晶粒不易长大,原因也是由于BeO杂质的对晶界迁移的钉扎作用。在680 ℃,730 ℃,780 ℃,830 ℃和880℃退火,完成再结晶时间分别大约为2160 min,180 min,20 min,5 min,4 min。金属铍350℃下压缩发生{0001}基面滑移和{10 2}类孪晶变形,形变机理与室温相同,没有随温度升高而发生改变,仍保持金属铍特有的反常变形行为。

Abstract:

The microstructure evolution of beryllium which was deformed at the temperature of T = 350 ℃ and the strain rates of ε? = 10_^-3?s_^-1 was systematically studied during annealing by mean of hot compression and vacuum annealing experiment. The annealing temperature is from 680 ℃ to 880 ℃. The results show that the metal beryllium has a unique static recrystallization behavior. The new grains first occur bulge at the {10 2}<10 > tensile twin boundaries. The bulge mechanism is similar to prior grain boundary bulge by strain induced grain boundaries migration in the vicinity of prior grain boundaries. The pinning effect of BeO impurities on the prior grain boundary migration is the reason why the twin boundary bulge nucleation precedes to the grain boundary bulge nucleation. The twin boundary bulge nucleation and grain boundary bulge nucleation are the main nucleation mechanism of the metal beryllium static recrystallization, supplemented with intragranular nucleation and the particle stimulated nucleation of recrystallization. When annealed from 680 ℃ to 880 ℃, the beryllium deformed at 350 ℃ low temperature is able to achieve complete recrystallization microstructure of grain refinement, no recrystallization texture is formed in the recrystallization microstructure. Similarly, the recrystallization grains of the metal beryllium are difficult to grow due to the pinning effect of BeO impurities on grain boundary migration. Annealing at 680 ℃, 730 ℃, 780 ℃, 830 ℃ and 880 ℃, the recrystallization time is about 2160 min, 180 min, 20 min, 5 min and 4 min, respectively. The metal beryllium occurs {0001} basal plane slip and {10 2}<10 > twin deformation under compression at 350 ℃. The deformation mechanisms are same as that at room temperature, no change with temperature the increase of temperature, and keep typical abnormal deformation behaviors of the metal beryllium.