Cu50Zr42Al8合金的铸态组织及硬度的研究

采用铜模吸铸法制备了Cu50Zr42Al8的圆锥形块状非晶试样,利用X射线衍射（XRD）、金相显微镜（MeF3）、显微硬度计等分析手法表征材料的结构特点,观察试样的微观组织变化,测量试样的硬度.研究表明,冷却速率对Cu50Zr42Al8合金的铸态组织有很大的影响.由于冷却速率的不同,圆锥形试样的显微组织由表面到中心依次形成了表面非晶区、非晶-晶体过渡区和中心晶体区.晶体的尺寸和体积分数由表面到中心逐渐增加,具有梯度变化的特征.冷却速率不同,试样的显微硬度也不同,在晶体区内,中心部位的硬度高;非晶区中,中心部位的硬度较高;而介于晶体-非晶体之间的过渡区,硬度却较低.

Study on Microstructure and Hardness of Cu50Zr42Al8 Alloy As-cast

The taper samples of Cu_(50)Zr_(42)Al_8 amorphous alloy with high glass forming ability were prepared by suction-casting process with copper mold,which bottom diameter closes to 10 mm and length is 80 mm.X-ray diffraction (XRD) was used to characterize the evolution of structure, metallograghic microscope(MeF_3) was used to observe the microstructure and micro-sclerometer was used to test microhardness.The results show that the cooling rate has a great influence on the microstructure of Cu_(50)Zr_(42)Al_8 alloy as-cast,the microstructure of Cu_(50)Zr_(42)Al_8 alloy is different with different rate of cooling.From surface to center,the fully glassy region,glass/crystal composite region and full crystal region exist respectively.The crystal size and volume fraction increase gradually from surface to center. The rate of cooling is different,the test specimen microhardness is different either,in the crystal rigion and the amorphous region, the hardness is higher than in center, but in the amorphous/crystal composite region ,the hardness is lower.