残余应力对W-Cu复合材料导热性能的影响

Effect of Residual Stresses on the Thermal Conductivity of W-Cu Composites

摘要:

用熔渗法制备的W-Cu复合材料在小批量生产时，发现熔渗结束后样品的热导率数据分散不稳定，受熔渗时摆放位置的影响很大。将熔渗结束后的样品退火，采取不同的方式冷却。用X射线衍射法测量其残余应力，用热脉冲法测量其热导率，研究了残余应力对材料导热性能的影响。结果表明：随冷却速度的加快，残余应力值增大，热导率降低。钨和铜的热膨胀系数相差较大，从高温冷到室温时两相收缩程度不一样，冷却速度过快时，在界面处产生残余应力，使材料的热导率降低。分析了残余应力对材料导热性能的影响及机制。

关键词:W-Cu复合材料 残余应力 热导率

Abstract:

The thermal conductivity of W-Cu composites is affected by the position where they were placed in during infiltrating. The W-Cu composites after infiltrating were kept at a certain temperature for some hours with the protection of hydrogen and then cooled down to room temperature by different means. By X-ray diffraction experiment, tungsten phase is found to be under compression and copper phase under tension. The value of the residual stresses increases with the cooling rate, while the thermal conductivity, inversely. The coefficient of thermal expansion(CTE) mismatch of tungsten and copper led to the significant amount of thermal stresses at the interface and low thermal conductivity. The effect of the residual stresses on the thermal conductivity, as well as its mechanism was analyzed.

Key words:W-Cu composites; residual stresses; thermal conductivity