摘要
针对粉末冶金铍铝合金开展了微屈服行为的研究;利用SEM、TEM研究了合金在微屈服过程中不同形变量下两相的位错形态变化和断口组织特征。结果表明:合金的微屈服强度较低;铍相在未发生微屈服至发生2个微应变时(2×10-6),位错很难发现;79个微应变时,晶内晶界均出现位错;121个微应变时,位错扩大运动连接成折线状;500个微应变时,位错缠结;拉伸断裂后,晶内的位错线被拉直,晶界附近区域的位错数量减少。与铍相不同,铝相在未屈服前,就已出现少量位错;2个微应变时,基体大面积发生塑性应变;当微应变增至79个时,在外载荷和热残余应力的驱动下,铝域内的位错聚集在界面处,致使位错切入铍相内,降低铍相的形变抗力。铍铝合金的断裂模式为脆性铍相的解理断裂和韧性铝相的韧窝断裂构成的混合型断裂。
Micro-yield behavior of powder metallurgical beryllium-aluminum alloys was researched.The dislocation changes of the two phases at different stains in the process of micro-yield of the alloys were studied by TEM,and the fracture character was observed by SEM.The results show that the Be-Al alloy exhibits a lower micro-yield strength;the dislocations are difficult to discover before micro-yield to reaching 2×10-6 stains in Be phase;when the stain reaches 79 × 10-6,the dislocations appear both in the grain and along the grain boundaries;the dislocations move and connect to lines after 121 × 10-6 stains;the dislocations tangle at 500 × 10-6 stains,which are straightened in the grain and decrease in the vicinity of grain boundary.Different from Be phase,a few dislocations of Al phase have appeared before micro-yield;when the stain reaches 2×10-6,large plastic strain occurs in Al phase;driven by the external load and thermal residual stress,the dislocations in Al phase gather at the interface and cause them cut into Be phase,reducing its deformation resistance.The failure mode of beryllium-aluminum alloys is brittle cleavage failure of beryllium regions combined with ductile dimple failure of aluminum regions.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2012年第10期1795-1798,共4页
Rare Metal Materials and Engineering
基金
国家自然科学基金资助项目(50761006)
宁夏大学科学研究基金项目(ZR1111)
关键词
粉末冶金铍铝合金
微屈服
位错
TEM
powder metallurgical beryllium-aluminum alloys
micro-yield
dislocation
TEM
