【作者】 李海山；

【导师】 葛继平；

【作者基本信息】 大连交通大学 ， 材料加工工程， 2005， 硕士

【摘要】 形变Cu-10％Cr-3％Ag原位复合材料经中频感应加热熔炼、室温线拉并配合中间热处理制备而成。本文对铸态及变形态材料的微观组织结构，强度，导电性进行了研究。 用扫描电镜观察发现，铸态时Cr相为树枝晶，在线拉过程中，树枝晶沿着线拉方向发生转动并在一端先开始变形成为蝌蚪状，最终变为弯曲薄片状纤维。随形变量增大，纤维得到细化。性能测试结果发现，随形变量增加，强度得到大幅度的提高，当形变量为2.92时，其极限抗拉强度值为485MPa，当形变量为6.2时，极限抗拉强度值为955MPa，分析认为这是由于界面强化和加工硬化为主的各种强化方式综合作用的结果；电阻率随形变量增大而稍稍增大，进行中间热处理后，则大幅度地减小。中间热处理的温度不同，最终材料的强度和导电性也相应地发生变化。形变量一定，温度太高或太低都会使得强度和导电性性能降低。中间热处理温度为420℃-550℃的试验中发现，随中间热处理温度的升高，热处理后进一步拉拔过的材料的电阻率先减小后增加，强度先增加后减小，经485℃热处理后，性能组合最佳。分析认为，变形使电阻率增大的原因是界面散射电阻的增大，中间热处理则主要是使杂质散射电阻减小，为此得出，室温线拉并配合适当中间热处理，可获得强度和导电性的较好结合。 观察测量发现，Ag在Cu-10％Cr-3％Ag原位复合材料中存在于Cu基体和Cr／Cu界面处，Cr纤维中没有或只有特别少的Ag存在。 形变Cu-10％Cr-3％Ag原位复合材料拉拔到直径为φ1.0mm的状态下几个较好的电导率和极限抗拉强度组合为：82.8％IACS／791 MPa(φ1mm、B工艺)、80.6％IACS／809 MPa(φ 1mm、A工艺)和78.4％IACS／950MPa(φ1mm、C工艺、485℃)。更多还原

【Abstract】 The Cu-10%Cr-3%Ag in situ composites that was melted in a vacuum induction furnace and machined by drawing at room temperature combined with intermediate heat treatments. The as-cast alloy and the deformed in situ composites’ microstructure, strength, electrical conductivity, and the relationship between them were studied. It was found from SEM conversation that Cr phase transferred from the dendrites in as-cast status to the shape of tadpole paralleling drawing direction which deformation started from one set of the dendrites. At last, they all become into fibers. And the fibers were curl and fold. The heavier the deformation is, the more and firmer the fibers are. It was found from strength and electrical conductivity test that with the increases of the deformation, the composites was greatly strengthened by some kinds of strengthening methods in which the interface strengthen and work hardening play the most important roles. The Ultimate Tensile Strength of the sample at η=2.92 was 485MPa and that of sample at η=6.2 was 955MPa. The resistivity was slightly increased during the deformation processes because of the increase of interface scattering. On the other hand, during the intermediate heat treatments, the solute atoms scattering resistivity was sharply decrease because the Cr atoms precipitate, so the resistivity of deformed composite is lower than that of the cast alloy.Almost all of the Ag atoms in deformation Cu-10%Cr-3%Ag in situ composite dissolve in Cu based matrix. Some Ag atoms exist in the interface of Cu/Cu or Cr/Cu.The intermediate heat treatments with different temperature (420°C-550°C)have different effects on the mechanical property and electrical conductivity;Test results show that as increase of intermediate heat temperature from 420°Cto 550°C, the conductivity decrease first and then increase, and the strengthincrease first and then decrease.The sample with intermediate heat temperature at 485°C has the best result.Some good combination of mechanical property and electrical risistivity of更多还原