中文摘要：

基于金属熔体结构的遗传性，激光熔池的快速熔凝导致粉末的晶化状态可能会对最终成形件的晶化产生重要影响，理清其影响规律对于制备大块非晶合金具有重要意义．本文选取等离子旋转电极法所制粉末和1000K退火态粉末为沉积材料，采用激光立体成形技术沉积Zr55Cu30Al10Ni5块体非晶合金，考察了粉末中已有晶化相对熔池及热影响区晶化行为的影响．结果发现，原始粉末组织由非晶相及粗大的A15Ni3zr2相组成；当激光线能量较低时，相应熔覆层的熔池和热影响区皆含有A15Ni3Zr2相；随着线能量的提高，熔池中Al5Ni3Zr2相消失，保持了非晶态，但热影响区晶化加重，并有大量Al5Ni3Zr2相析出；当采用退火态粉末时，即使线能量较小，相应熔覆层仍主要由非晶构成，几乎无Al5Ni3Zr2相析出．这是由于原始粉末在退火时其微观结构发生重排，与Al5Ni3Zr2相关的原子短程／中程有序结构减少，导致己沉积层非晶区的热稳定性提高，不利于A15Ni3Zr2相析出．可见，提高线能量将会加剧非晶沉积体的晶化，而粉末中的Al5Ni3Zr2团簇相状态对Zr55Cu30Al10Ni5合金沉积层的晶化有重要影响．

英文摘要：

Laser solid forming （LSF） is a viable and promising manufacturing technique for preparing bulk metallic glasses （BMGs） without size limitation. Owing to the structural heredity of alloy melts, the crystallization characteristic of the powder has an important influence on that of the deposit during LSF process. In this work, the as-prepared Zr55Cu30Al10Ni5 （Zr55） alloy powder and the Zr55 alloy powder annealed at 1000 K are used for LSF of Zr55 BMGs. The influence of the crystallization characteristic of Zr55 alloy powder on the crystallization behavior of the remelted zone （RZ） and heat affected zone （HAZ） in the deposit are investigated, It is found that the as-prepared Zr55 powder prepared by plasma rotating electrode process （PREP） is composed of the amorphous phase and Al5Ni3Zr2 phase. When the heat input of laser is low, there exist some Al5Ni3Zr2 residual phases in the amorphous matrix in the RZ, and there appear some Cul0ZrT, CuZr2 and NiZr2 phases besides the Al5Ni3Zr2 phase in the HAZ for the deposit fabricated by as-prepared Zr55 powders. With the increase of the heat input of laser, the RZ remains the amorphous state since the Al5Ni3Zr2 phase is completely remelted, while there are a large quantity of Al5Ni3Zr2 phases and some other crystallization phases precipitated in the HAZ because the heating and cooling rate decrease in the HAZ during LSF. Fabricated by the fully crystallized annealed powder, the deposit is mainly of the amorphous phase, and almost no Al5Ni3Zr2 phase is found even if the incident laser power is low. It is shown that the crystallization of the deposit fabricated by the annealed powder at the low heat input does not change remarkably with the increase of the deposited layers. The Zr55 deposit with five deposited layers could still keep large volume fraction of amorphous phase. This is mainly because the powder experiences the structure relaxation entirely during the annealing treatment, and the volume fraction of the short/medium-range ordered structure ass