基于硅模具的锆基非晶合金微成形可靠性分析

Reliability analysis of micro-forming of Zr-based metallic glass by silicon molds

研究了硅模具的破碎原因,利用自主研制的非晶合金超塑性微成形试验机,对Zr65Cu17.5Ni10Al7.5非晶合金进行了大量超塑性微小零件成形实验.随机抽取了125组实验结果进行了统计分析,结果表明:90.70%的硅模具发生破碎时应力值低于40MPa,其中,46.51%的破碎行为发生在瞬间载荷为20 MPa、应变为0.1附近区域;39.53%的破碎行为发生在瞬间载荷为25MPa、应变为0.5附近区域.这两个区域恰好处于微成形各过渡阶段,材料的流动方向和速率发生明显改变,表明模具受力方向突变和局部应力增大是导致破碎的主要原因.结合DEFORM 3D仿真分析,得出利用夹具、增大坯料尺寸、增大模具尺寸可减少硅模具破碎几率,增加工艺可靠性.

Using the self-developed of amorphous alloy superplastic micro-forming machine, the rea- sons why silicon molds brake were investigated during massive superplastic forming experiment of Zr^sCure. sNi^0A175 amorphous alloy micro-components. The experimental results from sampled ran- domly 125 groups were summed up. Results show that 90.70% of the silicon mold break at a stress value below 40 MPa. 46.51% of the breaking occurs around 20 MPa stress, 0.1 strain value. In addi- tion, 39.53% of the breaking occurs around 25 MPa stress, 0.5 strain value. The two values areas are exactly at the transition of the various stages during micro-forming, where the direction and rate of flow of material change significantly, which indicate that the main reasons of breaking are the sudden change of direction of the force on mold and the increases of the local stress. Then the other reasons of silicon molds bing broken combined with the DEFORM 3D simulation were analyze. It is concluded that the probability of the broken molds can be reduced by using the fixture and increasing the blank size and mold size.