The electron source needs to be a metal, and the usual choice is aluminium.

电子源应该是一种金属材料，通常选用铝。

youdao

The component defines at least part of an alloy flow path for the flow of aluminium alloy from a pressurized source of substantially molten aluminium alloy of the machine to the die cavity.

该组件定义至少一个用于铝合金从大量的机器铝合金熔体压力的来源流向型腔合金流动路径的一部分。

youdao

In the Middle Ages it was discovered to be a rich source of aluminium sulphate - a crucial raw material used as a fixing agent in dyeing cloth.

BBC: Time team battles tide

Both, the housing and the potentiometer control as well as the rotary switch for selecting the source are made of anodised aluminium, while the front panel of the housing and the controls are milled from solid material.

ENGADGET: Sennheiser unveils HDVA 600 analog headphone amp, asks for $1,600

Mr Morgan said that since the jobs at Anglesey Aluminium can only therefore be saved by having a specific and reliable energy source, the assembly government, the company, and the Department of Trade and Industry are looking at the option of building a small to medium sized power plant.

BBC: NEWS | UK | Wales | North West Wales | Power station 'deal to save jobs'