碳化钛弥散强化钾钨合金的制备、力学性能及其抗瞬态热冲击能力研究

Preparation of KW–TiC Alloy, and Its Mechanical Properties, Resistance to Transient Thermal Shock

通过机械合金化法和热轧加工,制备出变形量为70%的碳化钛弥散强化钾钨(KW-TiC)合金。相比纯钾钨(KW)合金,KW-TiC合金的晶粒尺寸显著降低,力学性能显著提高,具有2500MPa的抗弯强度和更高的变形能力。KW-TiC和KW都具有低于250°C的韧脆转变温度(DBTT)。经过真空下1800°C、1h退火后,KW-TiC具有与KW类似的搭晶状组织,但晶粒尺寸比KW更细小。在电子束热冲击装置上,对KW-TiC和KW进行0.44~0.88GW/m2的瞬态热冲击测试。在此能量密度下,KW-TiC与KW呈现出不同的开裂形貌,但由于TiC的存在降低了合金热导率,导致KW-TiC表面出现局部熔化现象。

KW-TiC alloy was fabricated through mechanical alloying method and hot rolling process.Compared with KW alloy,the KW-TiC alloy exhibited bending strength of 2500MPa and higher deformation capacity.Both KW-TiC and KW had ductile-to-brittle transition temperature below 250°C.Annealing at 1800°C for 1 hour,no significant equiaxed recrystallization was observed.KW-TiC alloy had the similar structure to KW,but its size was much smaller.The thermal shock resistance of both alloys was characterized by an electron beam facility.Thermal shock tests were conducted at absorbed power densities from 0.44GW/m2 to 0.88GW/m2.After the tests,the KW-TiC and KW alloys showed different crack morphology.However,the existence of TiC reduced the thermal conductivity of KW-TiC alloy,which resulted in the surface melting.