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一般地认为,钒、铌、钽、铬、钼、钨和铼是难熔金属类;而钛、锆、铪和铍是活性金属类。在难熔金属中,研究最多的是铌、钽、钼和钨。在五十年代初期,人们把这些金属看成是奇异的金属,今天却成为宇宙时代的基础金属。钨钼钽铌具有很高的熔点,高的高温强度和良好的耐蚀性能以及其他的独特的性能,在国民经济一些部门中和国防工业中占有重要地位。五十年代中期到六十年代末期可以说是难熔金属的黄金时代。这一时期,由于宇航
It is generally believed that vanadium, niobium, tantalum, chromium, molybdenum, tungsten and rhenium are refractory metals; and titanium, zirconium, hafnium and beryllium are active metals. Among the refractory metals, the most studied are niobium, tantalum, molybdenum and tungsten. In the early 1950s, people saw these metals as singular metals, but today they are the foundations of the universe. Tungsten Molybdenum Tantalum niobium has a high melting point, high temperature strength and good corrosion resistance as well as other unique properties, in some sectors of the national economy and defense industry occupies an important position. The mid-fifties to the late sixties can be said that the golden age of refractory metals. This period, due to aerospace