铝合金中氢效应的正电子湮没研究  

POSITRON ANNIHILATION STUDY ON HYDROGEN EFFECT OF THE ALLOY ALUMINIUM

作　　者：吴奕初[1] 滕敏康[1] 夏元复[1] 

机构地区：[1]南京大学物理系

出　　处：《南京大学学报（自然科学版）》1994年第3期439-443,共5页Journal of Nanjing University（Natural Science）

摘　　要：铝合金的氢脆和应力腐蚀开裂是受到广泛重视的课题．本文采用正电子湮没（ＰＡ）技术研究了ＬＣ４铝合金在慢拉伸动态充氢时，在３．５％ＮａＣｌ＋２００ｍｇ／１Ａｓ２Ｏ３介质中，多普勒展宽（Ｄｏｐｐｌｅｒｂｒｏａｄｅｎｉｎｇ）Ｓ参数的变化．实验发现在阴极极化下，Ｓ参数下降．这是由于相当部分原来是深阱的正电子陷阱转为为浅阱，或者充氢后产生新的正电子陷阱引起，Ｍｇ与Ｈ互作用形成ＭｇＨ２是形成脆化的可能原因；在阳极极化下也观察到Ｓ参数下降，作者认为这是由于此时ＧＰ区（主要是ＭｇＺｎ２）的优先溶解．Previous experiments indicated that hydrogen-charging in alloy aluminium leads to defects. The microstructure variations due to hydrogen effect in the LC4 alloy aluminium sample were investigated by the positron annihilation technique. The sample contains 5.24 wt% Zn, 2.11 wt% Mg, 1.77 wt% Cu, 0.44 wt% Cr and 0.33 wt% Mn. It was deformed under a slow strain rate of 4×10-7/sec, and hydrogen was simultaneously introduced by both a catholically hydrogen-charging and an anodically hydrogen-charging process with a current density of 20 mA / cm2. The S-parameter values under different charging time were measured until' the sample was broken.The experimental results indicate that when the 100℃-underaged samples are deformed during hydrogen-charging process in a solution of 3.5% NaCl+250mg / 1 As2O3. in the case of cathode polarizahon, S-parameter decreases with decreasing potential or increasing charging time. However, in the case of anode polarization, S-parameter of the hydrogen-charged samples decreases about 2.0% relative to that of the hydrogen-qree samples, and it does not change with anode potential. It is suggested that under the anode polarization, the dissolution of some GP zones (MgZn2) may result in the decrease of S-parameter; conversely, under the cathode polarization, the formation of a hydride (MgH2) may result in the decrease of S-parameter.

关 键 词：铝合金 氢 正电子湮没 

分 类 号：TG146.21[一般工业技术—材料科学与工程]