Electron Beam Melting and Improvement of Mechanical Properties of Pure Tantalum

从基本拉伸模量、力学性能及其温度和应变速率依赖性等工程角度，研究了温度和应变速率对电子束熔炼纯钽板材拉伸屈服和流动的影响。在某些特定的拉伸试验和退火条件下，电子束熔融钽的屈服行为明显。拉伸塑性流动的温度依赖性的临界温度为约0.15 T/Tm，与0.12 T/Tm相比略高。在最高应变速率条件下测量的均匀延伸率方面，在250 K以下观察到明显的脆性，在250 K以下观察到电子束熔化钽的韧脆转变。在低于380 K的温度下根据纯钽的屈服或流动获得的活化能和活化体积与关于通过粉末冶金技术生产的纯钽测量的那些值几乎相同。

Effect of the temperature and strain rate on the tensile yielding and flow of pure tantalum plate, produced by electron beam melting method, was experimentally studied mainly from an engineering viewpoints of fundamental tensile m, mechanical properties and their temperature and strain rate dependency. Sharply projected yielding behaviors were here seen for electron beam melted tantalum under certain specified tensile testing and annealing conditions. Critical temperature for the temperature dependence of the tensile plastic flow was about 0.15 T/Tm which was slightly higher as compared to 0.12 T/Tm of pure tantalum produced by powder metallurgy.Distinctive brittleness was observed below 250 K regarding the measurements of the uniform elongation for the highest strain rate conditions and ductile to brittle transition was seen for the electron beam melted tantalum at the temperatures ranging from 300 to 250 K.Activation energy and activation volume obtained at temperatures below 380 K in accordance with the yielding or flow of pure tantalum were almost the same as those values measured regarding pure tantalum produced by power metallurgical technology.