There are too many factors, but the shape, size, number and distribution can be used to determine which link causes it. If you say the YT14 alloy, if the above holes, you can start from the following aspects, 1, raw materials, dirty and oxygen content is too high, impurities content, 2, sintering.
If the hole shape of the dirty and dirty, you can see some holes around a circle with cobalt layer, small holes are filled with cobalt, cobalt pool formation, if not pressure, hole like strip shape feiyan. YT14 containing titanium, titanium with high oxygen affinity, if high oxygen content and sintering process is not reasonable, high temperature gas production could not be drained to form holes, you see the sintering process is reasonable, the presence of liquid phase before the vacuum degree is not high enough. In addition, this kind of degassing is incomplete, and the hole is more in the edge of the product.