Cu坯料纯度对Cu46Zr42Al7Gd5合金非晶形成能力与显微硬度的影响

摘要

A bulk amorphous Cu46Zr42Al7Gd5 alloy with a diameter of 3 mm was prepared by copper mould sucking cast. The effect of copper billet purity on the glass forming ability, thermal stability and microhardness of the alloy was studied. The bulk amorphous Cu46Zr42Al7Gd5 alloy with a diameter of 3 mm can be prepared using copper billet with lower purity to replace copper billet with higher purity in the proportion of 25% and 50%, while the alloy shows the characteristic of crystalline in the proportion of 75% or above. When the copper billet with higher purity is replaced with lower purity billet in the proportion of 25%, the glass transition temperature is about 669 K, the crystallization temperature is about 749 K and the supercooled region is about 80 K. When the copper billet with higher purity is replaced with lower purity billet in the proportion of 50%, the glass transition temperature is 684 K, crystallization temperature is 751 K and supercooled region is 67 K. The alloys all keep amorphous structure after heat treatment at 573 K for 1 h. The alloys in 25% proportion crystallize after heat treatment at 673 and 773 K for 1 h, which consist of substrate and second fine phase and have higher microhardness. The alloys in 50% proportion also consist of substrate and second fine phase, and have higher microhardness after heat treatment at 673 K for 1 h. There are two kinds of microstructures after heat treatment at 773 K for 1 h, white area consists of substrate and second fine phase, and grey area consists of white phase and grey phase. The microhardness increases sharply.%采用铜模吸铸法制备直径为3 mm的Cu46Zr42Al7Gd5块体非晶合金;研究Cu坯料纯度对该合金非晶形成能力、热稳定性和显微硬度的影响.结果表明:采用纯度较低的Cu坯料,分别以25%和50%的比例替代纯度较高的Cu坯料后,仍可制备直径为3 mm的非晶态合金;当替代比例提高到75%或更高时,合金呈现完全晶态相;当替代比例为25%时,合金的玻璃化转变温度为669 K,晶化温度为749 K,过冷液相区为80 K;当替代比例为50%时,合金的玻璃转化温度为684 K,晶化温度为751 K,过冷液相区为67 K;两种替代比例(25%和50%)的合金经573 K保温1 h热处理后,仍然保持非晶态结构;当替代比例为25%时,合金经673和773 K热处理后,合金由基体及弥散分布于其上的第二相组成,显微硬度明显提高;当替代比例为50%时,经673 K处理后,合金由基体及不均匀弥散分布于其上的第二相组成,显微硬度有所提高,而经773 K处理后,由第二相弥散分布于白色基体的白色区域和由细小白、灰两相混合组成的灰色区域组成,显微硬度大幅度提高.