Research on Powder Forming of Metal Matrix Composite for High Density and High Strength

(1)设计并制造了一台多滑枕液压机，用于研究薄壁杯形件和带箔件的摩擦成形过程。(2)采用摩擦挤压薄壁杯形件的方法，研究了异种金属板料的成形和复合过程。用于不同金属板的各种组合的包覆杯可以以面积减小率Re= 90%和小于约2.4GPa的冲压压力形成。(3)绿色坯密度d_o= 90%时，铝、钛、铜和铁的压制压力分别为0.3、0.7、0.8和0.9 GPa。铝和钛的薄壁杯形件可成形为相对密度为98%。(4)研究了用铝粉生产带箔的摩擦减薄工艺。在挤压比R=200时，用相当低的冲压压力就可以形成厚度约为0.05毫米的非常薄的铝箔。在R=10-200时，箔带的极限抗拉强度约为250-300 MPa，比摩擦减薄法制备的固体块体箔带的极限抗拉强度高。(5)将与10、20和30重量%的氧化铝粉末混合的铝粉压制成相对密度约为90%的圆柱形绿色零件，并且可以通过常规的反向挤压和摩擦挤压形成薄壁杯。将铝和氧化铝粉末混合物压制成圆柱形零件，在600 ℃烧结，用这两种挤压工艺都可以挤压成薄壁杯形件。两种挤压工艺所形成的薄壁杯的相对密度在纯铝粉的情况下增加到约100%，但铝和氧化铝的混合粉末的密度不能充分增加。

(1) A multi-ram hydraulic press was designed and made for investigating the tribo-forming processes of a thin-walled cup and a strip-foil.(2) The forming and cladding of dissimilar metal sheets have been investigated by the tribo-extrusion process of thin-walled cup. The cladding cups for various combinations of dissimilar metal sheets could be formed with the reduction in area Re=90 % and the punch pressure less than about 2.4 GPa.(3) The compacting pressures for the green density d_o=90 % were about 0.3, 0.7, 0.8 and'O.9 GPa for an aluminium, a titanium, a copper and an iron, respectively, The thin-walled cups of aluminium and titanium could be formed with the relative density of 98 %.(4) The tribo-thinning process for producing a strip-foil from aluminium powder was investigated. The very thin aluminium foil of about 0.05 mm in thickness could be formed at the extrusion ratio R=200 with a considerably low punch pressure. The ultimate tensile strength of the foil strips formed at R=10-200 were about 250-300 MPa, which were rather higher than the value of that formed from the solid block by the tribo- thinning process.(5) The aluminium powder mixed with the alumina powder of 10, 20 and 30 wt% were compacted into the relative density of about 90 % into the cylindrical green parts and could be formed into the thin-walled cups by the conventional backward extrusion and the tribo-extrusion. The cylindrical parts which the powder mixtures of aluminium and alumina were compacted and sintered at 600ﾟC could be formed into the thin- walled cups by the both extrusion processes. The relative density of thin-walled cups formed by both the extrusion processes was increased up to about 100 % in the case of pure aluminium powder, but the density for mixture powder of aluminium and alumina could not be increased enough.