不同形态和热历史条件下Zr_(55)Al_(10)Ni_5Cu_(30)非晶合金的晶化行为

CRYSTALLIZATION BEHAVIOR OF Zr_(55)Al_(10)Ni_5Cu_(30) AMORPHOUS ALLOYS WITH DIFFERENT MORPHOLOGIES AND THERMAL HISTORY CONDITIONS

研究了不同形态Zr_(55)Al_(10)Ni_5Cu_(30)非晶合金(块体和粉末)在不同升温和冷却条件下的晶化行为.发现Zr_(55)Al_(10)-Ni_5Cu_(30)在不同热历史下的晶化行为有较大差别.对于块体非晶合金,在常规热处理条件下,合金的升温和冷却速率较低,Zr_(55)Al_(10)Ni_5Cu_(30)块体非晶合金在初始晶化温度Tx以上开始晶化,形成CuZr_2纳米晶.随着热处理温度的升高,晶粒尺寸增大,当热处理最终温度超过熔点后,合金在随炉冷却过程中形成了粗大的CuZr_2板条+板条间(CuZr_2)+(Zr,Cu,Al,Ni)共晶组织;在激光熔凝条件下,合金的升温和冷却速率较高,Zr_(55)Al_(10)Ni_5Cu_(30)块体非晶合金随单点熔凝次数的增加,晶化效应逐渐累加,热影响区中逐渐出现微米级球晶的弥散析出,并长大,随后失稳形成沿熔池边界带状分布,尺寸可达几百微米的等轴晶.对于粉末非晶合金,由于Zr_(55)Al_(10)Ni_5Cu_(30)非晶粉末的冷却强度不如块体非晶,冷却速率较块体低,造成粉末颗粒在激光熔凝过程中晶化为微米级的等轴枝晶,并随着激光能量的升高,等轴枝晶尺寸增大.

This work investigated the crystallization behavior of Zr55AlloNi5Cu30 amorphous alloy （bulk and powder with different morphologies） under different heating and cooling rate conditions, and has found that the crystallization behavior of Zr55AlloNisCu30 under different thermal history conditions was quite different. Under conventional heat treatment condition, the heating and cooling rates of the alloy were lower, the Zr55A110Ni5Cu30 bulk amorphous alloy began to crystallization above the outset crystallization temperature T~, the CuZr2 nanocrystalline was formed. With increasing temperature, its grain size became bigger, when exceeding the melting point, the thick CuZr2 lath＋eutectic organizations of lath （CuZr2）＋（Zr, Cu, A1, Ni） were formed under furnacecooling condition; under laser melting condition, however, the heating and cooling rates of alloy were higher, with increasing number of pulse frequency, the crystallization effect of Zr55AlloNi5Cu30 bulk amorphous alloy accumulated gradually, in heat affected zone spherulites were precipitated and grew up, subsequently became unstable and finally a belt of equiax crystals were formed along the weld pool boundary. For amorphous alloy powder, due to its poorer the cooling performance than bulk amorphous, the cooling rate was lower, causing the powder particles crystallized into equiaxed dendrite during laser melting process, and with increasing laser energy, the eauiaxed dendrite size increased_