CAJ | 학술논문

采用差热分析与阶梯铜模喷铸技术，研究不同冷却速率作用下Cu 70 Zr 30合金初生相尺寸、形貌以及包晶层厚度等的演化规律，讨论相选择与包晶转变的形成机理。结果表明：近平衡凝固条件下，差热分析试样中初生相形成与包晶转变的发生温度分别为1042℃和957℃，均滞后于平衡相图中相应的温度。由于包晶相两侧成分区间相差不大，且固态中原子扩散系数较小，因此，平均包晶层厚度仅为5μm，并存在残余的Cu 51 Zr 14初生相。铜模喷铸条件下，非平衡凝固组织中初生相结构未发生改变，但包晶转变得到有效抑制。随冷却速率提高，过冷度的增加有利于形核发生，初生相形貌从定向束状向等轴晶发生转变。
채용차열분석여계제동모분주기술，연구불동냉각속솔작용하Cu 70 Zr 30합금초생상척촌、형모이급포정층후도등적연화규률，토론상선택여포정전변적형성궤리。결과표명：근평형응고조건하，차열분석시양중초생상형성여포정전변적발생온도분별위1042℃화957℃，균체후우평형상도중상응적온도。유우포정상량측성분구간상차불대，차고태중원자확산계수교소，인차，평균포정층후도부위5μm，병존재잔여적Cu 51 Zr 14초생상。동모분주조건하，비평형응고조직중초생상결구미발생개변，단포정전변득도유효억제。수냉각속솔제고，과랭도적증가유리우형핵발생，초생상형모종정향속상향등축정발생전변。
The effects of cooling rate on the size and morphology of primary phase in Cu70Zr30 alloy, as well as the thickness of peritectic layer were investigated by differential thermal analysis and step copper mould spray casting techniques. The formation mechanisms of phase selection and peritectic transformation were discussed. The results show that the measured temperatures for primary phase and peritectic transformation are respectively 1042℃and 957℃in near-equilibrium solidification, which are smaller than the values from equilibrium phase diagram. Due to slight composition interval between the adjacent regions of peritectic phase and sluggish solute diffusion rate in solid, the average thickness of peritectic layer is merely 5μm with the presence of residual primary phase Cu51Zr14. The structure of primary phase is not changed by copper mould spray casting, while peritectic transformation is suppressed effectively. With increasing cooling rate, undercooling is enhanced to activate more nucleation events, which generates the morphology transition of primary phase from directionally bundle to equiaxed-grain microstructure.